Re: R: Re: FW: Re: what is a schema? what is a database?
Schema is a collection of databases. On Fri, Mar 28, 2008 at 6:00 PM, Nanni Claudio [EMAIL PROTECTED] wrote: I know I am a little late. From my experience with Oracle Database: ORACLE MYSQL(equivalent) --- DATABASEMYSQL INSTALLATION SCHEMA DATABASE So in Oracle a Database is an instance running on an Oracle installation, While with MySQL you need different installations to have different instances(mysqld). In my opinion Oracle naming approach is more correct, if you consider a Database as a RDBMS, anyway, MYSQL IS GREAT! Aloha! Claudio Nanni -Messaggio originale- Da: news [mailto:[EMAIL PROTECTED] Per conto di Thufir Inviato: mercoledì 5 marzo 2008 12.09 A: mysql@lists.mysql.com Oggetto: Re: FW: Re: what is a schema? what is a database? On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] Questo messaggio ed ogni suo allegato sono confidenziali e possono essere riservati o, comunque, protetti dall'essere diffusi. Se il ricevente non é il destinatario diretto del presente messaggio, é pregato di contattare l'originario mittente e di cancellare questo messaggio ed ogni suo allegato dal sistema di posta. Se il ricevente non é il destinatario diretto del presente messaggio, sono vietati l'uso, la riproduzione e la stampa di questo messaggio e di ogni suo allegato, nonché la diffusione del loro contenuto a qualsiasi altro soggetto * This message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If you are not the intended recipient, please contact the sender and delete this message and any attachment from your system. If you are not the intended recipient you must not use, copy or print this message or attachment or disclose the contents to any other person. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- I'm a mysql DBA in china. More about me just visit here: http://yueliangdao0608.cublog.cn
R: R: Re: FW: Re: what is a schema? what is a database?
According to what? From what you can read in Robert Sheldon SQL: A Beginner's Guide, page 35: As you might have noticed, nowhere in the structure of the SQL environment or a catalog is there mention of a database. The reason for this is that nowhere in the SQL:1999 standard is the term database defined. And from the rapid look I gave at the SQL:1999 standard he is right. Claudio Nanni Da: Moon's Father [mailto:[EMAIL PROTECTED] Inviato: lunedì 7 aprile 2008 10.24 A: Nanni Claudio Cc: Thufir; mysql@lists.mysql.com Oggetto: Re: R: Re: FW: Re: what is a schema? what is a database? Schema is a collection of databases. On Fri, Mar 28, 2008 at 6:00 PM, Nanni Claudio [EMAIL PROTECTED] wrote: I know I am a little late. From my experience with Oracle Database: ORACLE MYSQL(equivalent) --- DATABASEMYSQL INSTALLATION SCHEMA DATABASE So in Oracle a Database is an instance running on an Oracle installation, While with MySQL you need different installations to have different instances(mysqld). In my opinion Oracle naming approach is more correct, if you consider a Database as a RDBMS, anyway, MYSQL IS GREAT! Aloha! Claudio Nanni -Messaggio originale- Da: news [mailto:[EMAIL PROTECTED] Per conto di Thufir Inviato: mercoledì 5 marzo 2008 12.09 A: mysql@lists.mysql.com Oggetto: Re: FW: Re: what is a schema? what is a database? On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] Questo messaggio ed ogni suo allegato sono confidenziali e possono essere riservati o, comunque, protetti dall'essere diffusi. Se il ricevente non é il destinatario diretto del presente messaggio, é pregato di contattare l'originario mittente e di cancellare questo messaggio ed ogni suo allegato dal sistema di posta. Se il ricevente non é il destinatario diretto del presente messaggio, sono vietati l'uso, la riproduzione e la stampa di questo messaggio e di ogni suo allegato, nonché la diffusione del loro contenuto a qualsiasi altro soggetto * This message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If you are not the intended recipient, please contact the sender and delete this message and any attachment from your system. If you are not the intended recipient you must not use, copy or print this message or attachment or disclose the contents to any other person. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] -- I'm a mysql DBA in china. More about me just visit here: http://yueliangdao0608.cublog.cn Questo messaggio ed ogni suo allegato sono confidenziali e possono essere riservati o, comunque, protetti dall'essere diffusi. Se il ricevente non é il destinatario diretto del presente messaggio, é pregato di contattare l'originario mittente e di cancellare questo messaggio ed ogni suo allegato dal sistema di posta. Se il ricevente non é il destinatario diretto del presente messaggio, sono vietati l'uso, la riproduzione e la stampa di questo messaggio e di ogni suo allegato, nonché la diffusione del loro contenuto a qualsiasi altro soggetto * This message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If you are not the intended recipient, please contact the sender and delete this message and any attachment from your system. If you are not the intended recipient you must not use, copy or print this message or attachment or disclose the contents to any other person.
Re: R: Re: FW: Re: what is a schema? what is a database?
On Mon, Apr 7, 2008 at 1:24 AM, Moon's Father [EMAIL PROTECTED] wrote: Schema is a collection of databases. A schema is a definition of tables fields and their relationship. Kevin. -- [EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
R: Re: FW: Re: what is a schema? what is a database?
I know I am a little late. From my experience with Oracle Database: ORACLE MYSQL(equivalent) --- DATABASEMYSQL INSTALLATION SCHEMA DATABASE So in Oracle a Database is an instance running on an Oracle installation, While with MySQL you need different installations to have different instances(mysqld). In my opinion Oracle naming approach is more correct, if you consider a Database as a RDBMS, anyway, MYSQL IS GREAT! Aloha! Claudio Nanni -Messaggio originale- Da: news [mailto:[EMAIL PROTECTED] Per conto di Thufir Inviato: mercoledì 5 marzo 2008 12.09 A: mysql@lists.mysql.com Oggetto: Re: FW: Re: what is a schema? what is a database? On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] Questo messaggio ed ogni suo allegato sono confidenziali e possono essere riservati o, comunque, protetti dall'essere diffusi. Se il ricevente non é il destinatario diretto del presente messaggio, é pregato di contattare l'originario mittente e di cancellare questo messaggio ed ogni suo allegato dal sistema di posta. Se il ricevente non é il destinatario diretto del presente messaggio, sono vietati l'uso, la riproduzione e la stampa di questo messaggio e di ogni suo allegato, nonché la diffusione del loro contenuto a qualsiasi altro soggetto * This message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If you are not the intended recipient, please contact the sender and delete this message and any attachment from your system. If you are not the intended recipient you must not use, copy or print this message or attachment or disclose the contents to any other person. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
On Tue, 04 Mar 2008 09:48:03 -0600, Paul DuBois wrote: Apparently MySQL lacks this feature, but what feature is it lacking? There's no equivalent to: SELECT * FROM database.schema.table; In MySQL, the two are equivalent. The keyword DATABASE or DATABASES can be replaced with SCHEMA or SCHEMAS wherever it appears. Right, but that wasn't exactly what I was asking. I'm fairly familiar with MySQL but am trying to understand this criticism of it. Not being familiar with other databases I have no reference point. What are they getting at? Why would you want to do a query of: SELECT * FROM database.schema.table; Obviously, this is non-sense in MySQL, where database == schema. -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: FW: Re: what is a schema? what is a database?
On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
Hi Thufir, all ! Thufir wrote: On Tue, 04 Mar 2008 09:48:03 -0600, Paul DuBois wrote: [[...]] In MySQL, the two are equivalent. The keyword DATABASE or DATABASES can be replaced with SCHEMA or SCHEMAS wherever it appears. Right, but that wasn't exactly what I was asking. I'm fairly familiar with MySQL but am trying to understand this criticism of it. Not being familiar with other databases I have no reference point. What are they getting at? Why would you want to do a query of: SELECT * FROM database.schema.table; Obviously, this is non-sense in MySQL, where database == schema. AFAIK, this all goes back to an ANSI standard for SQL in the mid-80s. That standard had a CREATE SCHEMA command, and it served to introduce multiple name spaces for table and view names. All tables and views were created within a schema. I do not know whether that version defined some cross-schema access to tables and views, but I assume it did. AFAIR, no product (at least back then) really implemented it, that whole concept was more theory than practice. OTOH, ISTR this version of the standard did not have the concept of a user or a CREATE USER command, so there were products that used the concept of a user (who then had his own name space for tables and views) to implement their equivalent of schema. This is an area where systems differ. As far as administration is concerned, this should not matter too much, because here you have differences anyway. As far as you look at application code, you only have to care about cases where one application accesses tables from multiple name spaces. AFAIK, all systems support a syntax name space.local identifier, and for this it should not matter whether the name space is that of a user, a schema, or a database. (I do not claim having done a complete research, so maybe there are systems which differ in this regard.) I have not heard of a three level naming scheme yet. Regards, Jörg -- Joerg Bruehe, Senior Production Engineer MySQL AB, www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
Sorry. An example of a fully qualified SQL Server object name is: SELECT * FROM Server123.Database456.Sales.Product The object Server123.Database456.Manufacture.Product is a different table from Server123.Database456.Sales.Product. Joerg Bruehe in his post called a schema a namespace, I believe he is correct. -Original Message- From: news [mailto:[EMAIL PROTECTED] On Behalf Of Thufir Sent: Wednesday, March 05, 2008 3:09 AM To: mysql@lists.mysql.com Subject: Re: FW: Re: what is a schema? what is a database? On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
my understanding is that Namespace is a defined grouping of classes http://m5.eecs.umich.edu/docs/namespaceMySQL.html where MySQL triggers a namespace must be unique within the schema (database). http://markmail.org/message/m5icpi2luv6baijt?q=Joerg+Bruehe+AND+namespace +AND+definitionpage=1refer=tpuhsicnt5h5helm Buena Suerte/Viel Gluck Martin - Original Message - From: Garris, Nicole [EMAIL PROTECTED] To: mysql@lists.mysql.com Sent: Wednesday, March 05, 2008 10:33 AM Subject: Re: what is a schema? what is a database? Sorry. An example of a fully qualified SQL Server object name is: SELECT * FROM Server123.Database456.Sales.Product The object Server123.Database456.Manufacture.Product is a different table from Server123.Database456.Sales.Product. Joerg Bruehe in his post called a schema a namespace, I believe he is correct. -Original Message- From: news [mailto:[EMAIL PROTECTED] On Behalf Of Thufir Sent: Wednesday, March 05, 2008 3:09 AM To: mysql@lists.mysql.com Subject: Re: FW: Re: what is a schema? what is a database? On Tue, 04 Mar 2008 07:21:21 -0800, Garris, Nicole wrote: My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. In your two examples: SELECT * FROM server.sales.schema.product; SELECT * FROM server.product.schema.product; I'm a bit tired, so maybe I'm not seeing it, but what goes in the schema place holder? -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
Hi ! Martin Gainty wrote: my understanding is that Namespace is a defined grouping of classes http://m5.eecs.umich.edu/docs/namespaceMySQL.html My use of the term name space was much more generic, similar to how compilers use it: When you define a record type (C: struct, Pascal: record, ...), you create (and enter) a new name space, the field names are valid within that record type only, and different record types can have fields with identical names without conflict. Similar each function (procedure, subroutine, ...) opens a new name space for its own local variables. Within SQL, each CREATE TABLE opens a new name space: column names are valid within that table only, and different tables may use the same name for different columns. (Yes, I know you can omit table. in a SQL statement if the column name is unique among the tables in that statement - you get the idea.) And similar, a schema in that ANSI SQL standard opened a name space for tables and views, and AFAIR that was its only purpose. (No, I will not try to dig up that standard - its schema concept had no practical relevance in products back then.) Jörg -- Joerg Bruehe, Senior Production Engineer MySQL AB, www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
On Wed, 05 Mar 2008 15:01:12 +0100, Joerg Bruehe wrote: I have not heard of a three level naming scheme yet. Aha, thanks for the history, helps to put what I was reading into context. -Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
On Mon, 03 Mar 2008 14:20:58 -0500, Martin Gainty wrote: http://dev.mysql.com/doc/refman/5.0/en/schemata-table.html According to MYSQL doc: A schema is a database That contradicts the following claim (to my reading): A true fully (database, schema, and table) qualified query is exemplified as such: select * from database.schema.table http://en.wikipedia.org/wiki/ Comparison_of_relational_database_management_systems#Databases_vs_Schemas_.28terminology.29 What' I'm familiar with is: SELECT * FROM database.table; That's ok, that makes sense, this is how MySQL does it and is how I've been doing it. Some databases do it differently, apparently. Apparently MySQL lacks this feature, but what feature is it lacking? There's no equivalent to: SELECT * FROM database.schema.table; thanks, Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
FW: Re: what is a schema? what is a database?
My experience (Oracle, PostgreSQL, MySQL, SQL Server) is that every DBMS is different in this regard. Microsoft's SQL Server works like this: A SQL Server instance (server) can have many databases. A database can have many schemas, schema simply being a grouping for objects in a database. In a SQL Server 2005 database, there can be two tables named Product if one is in the schema Sales and the other is in the schema Manufacture. The two tables are Sales.Product and Manufacture.Product. A fully qualified SQL Server object name is server.database.schema.object. -Original Message- From: news [mailto:[EMAIL PROTECTED] On Behalf Of Thufir Sent: Tuesday, March 04, 2008 12:58 AM To: mysql@lists.mysql.com Subject: Re: what is a schema? what is a database? On Mon, 03 Mar 2008 14:20:58 -0500, Martin Gainty wrote: http://dev.mysql.com/doc/refman/5.0/en/schemata-table.html According to MYSQL doc: A schema is a database That contradicts the following claim (to my reading): A true fully (database, schema, and table) qualified query is exemplified as such: select * from database.schema.table http://en.wikipedia.org/wiki/ Comparison_of_relational_database_management_systems#Databases_vs_Schema s_.28terminology.29 What' I'm familiar with is: SELECT * FROM database.table; That's ok, that makes sense, this is how MySQL does it and is how I've been doing it. Some databases do it differently, apparently. Apparently MySQL lacks this feature, but what feature is it lacking? There's no equivalent to: SELECT * FROM database.schema.table; thanks, Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
At 8:58 AM + 3/4/08, Thufir wrote: On Mon, 03 Mar 2008 14:20:58 -0500, Martin Gainty wrote: http://dev.mysql.com/doc/refman/5.0/en/schemata-table.html According to MYSQL doc: A schema is a database That contradicts the following claim (to my reading): A true fully (database, schema, and table) qualified query is exemplified as such: select * from database.schema.table http://en.wikipedia.org/wiki/ Comparison_of_relational_database_management_systems#Databases_vs_Schemas_.28terminology.29 What' I'm familiar with is: SELECT * FROM database.table; That's ok, that makes sense, this is how MySQL does it and is how I've been doing it. Some databases do it differently, apparently. Apparently MySQL lacks this feature, but what feature is it lacking? There's no equivalent to: SELECT * FROM database.schema.table; In MySQL, the two are equivalent. The keyword DATABASE or DATABASES can be replaced with SCHEMA or SCHEMAS wherever it appears. Examples: CREATE DATABASE = CREATE SCHEMA SHOW DATABASES = SHOW SCHEMAS -- Paul DuBois, MySQL Documentation Team Madison, Wisconsin, USA MySQL AB, www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
http://dev.mysql.com/doc/refman/5.0/en/schemata-table.html According to MYSQL doc: A schema is a database Wikopedia says a Schema is defined as: Pronounced as skee-ma, the structure of a database system, described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables.Schemas are generally stored in a data dictionary. Although a schema is defined in text database language, the term is often used to refer to a graphical depiction of the database structure.[1] and further categorised to: Conceptual Schema: A Map of concepts and their relationships Logical Schema a map of entities and their attributes and relations Physical Schema an implementation of a logical schema Schema Object such as oracle DB Object M-- - Original Message - From: Thufir [EMAIL PROTECTED] To: mysql@lists.mysql.com Sent: Sunday, March 02, 2008 3:46 AM Subject: what is a schema? what is a database? I've been referencing a variety of sources, including wikipedia. What I know about a schema is that in SQLite the .schema command will show the the SQL structure of that databases tables, which would be analogous to DESCRIBE foo in MySQL (with the difference that SQLite shows all tables in one go). The schema is the structure of the database? I'm trying to understand what the wikipedia article is driving at. I would assume that only tables which are related go in the same database? That would my instinct, at least. Tables which are unrelated going into a different database. The quote from wikipedia: The problem that arises is that former MySQL users will mistakenly create multiple databases for one project. In this context MySQL databases are analogous in function to Postgres-schemas, insomuch as Postgres lacks off- the-shelf cross-database functionality that MySQL has. Conversely, Postgres has rightfully applied more of the specification, in a sane- bottom-up approach, implementing cross-table, cross-schema, and then left room for future cross-database functionality. http://en.wikipedia.org/wiki/ Comparison_of_relational_database_management_systems#Databases_vs_Schemas_.2 8terminology.29 thanks, Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: what is a schema? what is a database?
Yes, you are exactly right. The schema is the structure of the database. Keith I've been referencing a variety of sources, including wikipedia. What I know about a schema is that in SQLite the .schema command will show the the SQL structure of that databases tables, which would be analogous to DESCRIBE foo in MySQL (with the difference that SQLite shows all tables in one go). The schema is the structure of the database? I'm trying to understand what the wikipedia article is driving at. I would assume that only tables which are related go in the same database? That would my instinct, at least. Tables which are unrelated going into a different database. The quote from wikipedia: The problem that arises is that former MySQL users will mistakenly create multiple databases for one project. In this context MySQL databases are analogous in function to Postgres-schemas, insomuch as Postgres lacks off- the-shelf cross-database functionality that MySQL has. Conversely, Postgres has rightfully applied more of the specification, in a sane- bottom-up approach, implementing cross-table, cross-schema, and then left room for future cross-database functionality. http://en.wikipedia.org/wiki/ Comparison_of_relational_database_management_systems#Databases_vs_Schemas_.28terminology.29 thanks, Thufir -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: What is a schema?
as far as I know a schema is a description of a database. [EMAIL PROTECTED] wrote: What is a schema? How is different from a database? -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
RE: What is a schema?
A schema is a the database design. Sometimes textual, sometimes visual definition of the database structure (tables, field types, defaults etc). The database is the physical implementation of the schema that holds the data. Bob -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 03, 2005 10:21 AM To: mysql@lists.mysql.com Subject: What is a schema? What is a schema? How is different from a database? -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: What is a schema?
On Wed, Aug 03, 2005 at 03:30:19PM +0100, Juan Pedro Reyes Molina wrote: as far as I know a schema is a description of a database. In ORACLE terms, a schema is a grouping of database objects (tables, indexes, and so on). It is synonymous with user in ORACLE. A given ORACLE instance can contain multiple schemas. -Jason Martin -- I'd love to, but I have to rotate my crops. This message is PGP/MIME signed. pgpjwHryLEUmW.pgp Description: PGP signature
RE: What is a schema?
Yes, I was going to echo this. In terms of MySQL, I think of the schema as the collection of DDL (data definition language) statements that make up your database. Table structure, column types etc. The schema, together with the actual data make up a database. Cheers, Jared. -Original Message- From: Jason Martin [mailto:[EMAIL PROTECTED] Sent: 03 August 2005 15:33 To: mysql@lists.mysql.com Subject: Re: What is a schema? On Wed, Aug 03, 2005 at 03:30:19PM +0100, Juan Pedro Reyes Molina wrote: as far as I know a schema is a description of a database. In ORACLE terms, a schema is a grouping of database objects (tables, indexes, and so on). It is synonymous with user in ORACLE. A given ORACLE instance can contain multiple schemas. -Jason Martin -- I'd love to, but I have to rotate my crops. This message is PGP/MIME signed. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: What is a schema?
[EMAIL PROTECTED] wrote on 08/03/2005 10:20:36 AM: What is a schema? How is different from a database? As I understand it, and some scholars may disagree with me, a schema is (most often) a description of a data structure. A database IS a data structure composed of tables and other possible components like views, stored procedures, triggers, etc. When we talk about schemas, we have to qualify the discussion with the level of the description you want to make. A table schema will detail the design of a table. It will have the column names, their data types, any default values, any constraints, any indexes (keys) etc. A database schema would discuss the details of the contents of a particular database. It would include things like the table names, where they are stored (for tables stored in different folders or on separate media), any relationships between the tables, and things at that level. Application level schemas would include such higher-level concepts as server names and the databases on them, other data sources (files, web streams, etc). So while some database systems (Oracle? I don't recall which.) identify the database level of data organization as a schema the more general use of the term is in the context of providing the physical description (the plan or scheme) of an organizational level. As I said, that's how I use the term and others will definitely have other opinions. Shawn Green Database Administrator Unimin Corporation - Spruce Pine
