Re: ResultSetMetaData question
On 7/7/22 2:03 AM, John English wrote: On 05/07/2022 17:26, Rick Hillegas wrote: In any event, as you've noticed, getLabelName() returns the same value as getColumnName() in Derby. So basically I need to write my own SQL parser for a sequence of SelectItems between SELeCT and FROM if I want to get the unaliased item? If you want getColumnName() and getLabelName() to return different values, then you will have to write some custom code.
Re: ResultSetMetaData question
On 05/07/2022 17:26, Rick Hillegas wrote: In any event, as you've noticed, getLabelName() returns the same value as getColumnName() in Derby. So basically I need to write my own SQL parser for a sequence of SelectItems between SELeCT and FROM if I want to get the unaliased item? -- John English -- This email has been checked for viruses by AVG. https://www.avg.com
Re: ResultSetMetaData question
On 7/4/22 11:50 AM, John English wrote: On 04/07/2022 16:21, Rick Hillegas wrote: I'm afraid I don't understand your results. When I run your experiment, "2" is the name and label of the second column of the query "SELECT country,count(*) FROM customer GROUP BY country ORDER BY country". Does the following give you what you want: SELECT country,count(*) AS "count(*)" FROM customer GROUP BY country ORDER BY country What I'm after if I have "x AS y" is a way of getting "x". I understood (incorrectly as it seems) that getColumnName() would give "x" and getColumnLabel() would give "y". As far as I can tell from experiments, both methods ALWAYS produce identical results. So I'm no longer sure why two different methods exist. As I understand the SQL Standard, the columns in query expressions (like SELECT statements) have "derived column names". The SQL Standard has no concept of a separate label name. The AS clause simply overrides the derived column name. The original authors of the ResultSetMetaData interface clearly imagined some distinction between getColumnName() and getColumnLabel(), but that distinction is not in the SQL Standard and it isn't clarified by either the ResultSetMetaData javadoc or the JDBC 4.3 spec. Maybe there is some corresponding distinction in the older ODBC spec which inspired the first JDBC spec. In any event, as you've noticed, getLabelName() returns the same value as getColumnName() in Derby.
Re: ResultSetMetaData question
On 04/07/2022 16:21, Rick Hillegas wrote: I'm afraid I don't understand your results. When I run your experiment, "2" is the name and label of the second column of the query "SELECT country,count(*) FROM customer GROUP BY country ORDER BY country". Does the following give you what you want: SELECT country,count(*) AS "count(*)" FROM customer GROUP BY country ORDER BY country What I'm after if I have "x AS y" is a way of getting "x". I understood (incorrectly as it seems) that getColumnName() would give "x" and getColumnLabel() would give "y". As far as I can tell from experiments, both methods ALWAYS produce identical results. So I'm no longer sure why two different methods exist. -- John English -- This email has been checked for viruses by AVG. https://www.avg.com
Re: ResultSetMetaData question
I'm afraid I don't understand your results. When I run your experiment, "2" is the name and label of the second column of the query "SELECT country,count(*) FROM customer GROUP BY country ORDER BY country". Does the following give you what you want: SELECT country,count(*) AS "count(*)" FROM customer GROUP BY country ORDER BY country On 7/4/22 6:01 AM, John English wrote: I have a query SELECT COUNT(*) AS X FROM ... If I use ResultMetaData.getColumnLabel(), I get "X". If I use ResultMetaData.getColumnName(), I also get "X". Here is the output from a test program: Query: SELECT country,count(*) FROM customer GROUP BY country ORDER BY country Name = COUNTRY Label = COUNTRY Name = COUNT(*) Label = COUNT(*) columns = COUNT(*), COUNTRY Query: select country, count(*) as customers from customer group by country order by country asc Name = COUNTRY Label = COUNTRY Name = CUSTOMERS Label = CUSTOMERS columns = COUNTRY, CUSTOMERS I was hoping/expecting that getColumnName() would return "COUNT(*)" in the second case. Is there any way to get COUNT(*) short of parsing the query myself? Thanks,
