OPEN statement [ESQL] [SP]

Description

Opens a previously declared cursor to access information from the database.

Syntax

OPEN cursor-name
... [ USING [ DESCRIPTOR { sqlda-name | host-variable [, ...] } ] ]
... [ WITH HOLD ]

Parameters

Examples

Example 1

• Examples showing the use of OPEN in Embedded SQL:

1. EXEC SQL OPEN employee_cursor;
2. EXEC SQL PREPARE emp_stat FROM
'SELECT empnum, empname FROM employee WHERE name like ?';
EXEC SQL DECLARE employee_cursor CURSOR FOR emp_stat;
EXEC SQL OPEN employee_cursor USING :pattern;

Example 2

• An example from a procedure:

BEGIN
DECLARE cur_employee CURSOR FOR
  SELECT emp_lname
  FROM employee ;
DECLARE name CHAR(40) ;
OPEN cur_employee;
LOOP
FETCH NEXT cur_employee into name ;
   ...
END LOOP
CLOSE cur_employee;
END

Usage

By default, all cursors are automatically closed at the end of the current transaction (COMMIT or ROLLBACK). The optional WITH HOLD clause keeps the cursor open for subsequent transactions. The cursor remains open until the end of the current connection or until an explicit CLOSE statement is executed. Cursors are automatically closed when a connection is terminated.

The USING DESCRIPTOR sqlda-name, host-variable and BLOCK n formats are for Embedded SQL only.

If the cursor name is specified by an identifier or string, then the corresponding DECLARE CURSOR statement must appear prior to the OPEN in the C program; if the cursor name is specified by a host variable, then the DECLARE CURSOR statement must execute before the OPEN statement.

The optional USING clause specifies the host variables that are bound to the placeholder bind variables in the SELECT statement for which the cursor has been declared.

After successful execution of the OPEN statement, the sqlerrd[3] field of the SQLCA (SQLIOESTIMATE) is filled in with an estimate of the number of input/output operations required to fetch all rows of the query. Also, the sqlerrd[2] field of the SQLCA (SQLCOUNT) is filled in with either the actual number of rows in the cursor (a value greater than or equal to 0), or an estimate thereof (a negative number whose absolute value is the estimate). The sqlerrd[2] field is the actual number of rows, if the database server can compute this value without counting the rows.

None.

Standards

Permissions

• Must have SELECT permission on all tables in a SELECT statement or EXECUTE permission on the procedure in a CALL statement.

• When the cursor is on a CALL statement, OPEN causes the procedure to execute until the first result set (SELECT statement with no INTO clause) is encountered. If the procedure completes and no result set is found, the SQLSTATE_PROCEDURE_COMPLETE warning is set.

See also