A single row query retrieves at most one row from the database. A single row query SELECT statement may have an INTO clause following the select list and before the FROM clause. The INTO clause contains a list of host variables to receive the value for each select list item. There must be the same number of host variables as there are select list items. The host variables may be accompanied by indicator variables to indicate NULL results.
When the SELECT statement is executed, the database server retrieves the results and places them in the host variables.
If the query returns more than one row, the database server returns the SQLE_TOO_MANY_RECORDS error.
If the query returns no rows, the SQLE_NOTFOUND warning is returned.
For more information about errors and warnings returned in the SQLCA structure, see Initializing the SQL Communications Area.
For example, the following code fragment returns 1 if a row from the employee table is successfully fetched, 0 if the row doesn't exist, and -1 if an error occurs.
EXEC SQL BEGIN DECLARE SECTION; long int emp_id; char name[41]; char sex; char birthdate[15]; short int ind_birthdate; EXEC SQL END DECLARE SECTION; int find_employee( long employee ) { emp_id = employee; EXEC SQL SELECT emp_fname || ' ' || emp_lname, sex, birth_date INTO :name, :sex, birthdate:ind_birthdate FROM "DBA".employee WHERE emp_id = :emp_id; if( SQLCODE == SQLE_NOTFOUND ) { return( 0 ); /* employee not found */ } else if( SQLCODE < 0 ) { return( -1 ); /* error */ } else { return( 1 ); /* found */ } } |
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