Many thanks for helping.
While using SQLite dll Version 3.3.4 on Windows
- Multiple threads/processes access SQLite database,
- Each thread does some SELECTs, INSERTs or UPDATEs.
If for some single SELECT (where user input is used in SQL statement, so to
avoid SQL injection),
sqlite3_prepare()/sqlite3_bind_****()/sqlite3_step()/sqlite3_finalize() are
used
then in that case
Q1. Which one is preferable -> BEGIN TRANSACTION or BEGIN IMMEDIATE ?
Q2. In the sample code below, if I remove two statements containing "BEGIN
TRANSACTION;" and "COMMIT TRANSACTION;" then for how long lock will be
acquired i.e. at which point of time lock will be acquired and which point
of time lock will be released ?
Please throw some light on that.
Thanks
Rohit
/* Sample code */
sqlite3* pDB;
sqlite3_stmt* pStmt;
char* szError = 0;
char* szTail = 0;
if( sqlite3_open("test.db", &pDB) != SQLITE_OK )
{
printf("Couldn't open the database.\n");
exit(1);
}
string name;
/* get from user input */
name = "ABCD"; // for testing
nRet = sqlite3_exec(pDB, "BEGIN TRANSACTION;", 0, 0, &szError);
<<<<<<<<<<---------------
const char* szSQL = "SELECT id, name, birthdate FROM table1 WHERE name = ?;"
;
nRet = sqlite3_bind_text(mpVM, nParam, szValue, -1, SQLITE_TRANSIENT);
if( sqlite3_prepare(pDB, szSQL, -1, &pStmt, &szTail) != SQLITE_OK )
throw "sqlite3_prepare Failed";
if ( sqlite3_step(pStmt) == SQLITE_DONE )
{
int i=0;
int empid = sqlite3_column_int(pStmt, ++i);
string name = (const char*) sqlite3_column_text(pStmt, ++i);
double birthdate = sqlite3_column_double(pStmt, ++i);
/* print something */
std::cout << id << "-" << name << "-" << birthdate << endl;
}
nRet = sqlite3_finalize(pStmt);
nRet = sqlite3_exec(pDB, "COMMIT TRANSACTION;", 0, 0, &szError);
<<<<<<<<<<---------------
--
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