EXECUTE Statement [ESQL]

Syntax

Syntax 1

EXECUTE statement-name
... [ { USING DESCRIPTOR sqlda-name | USING host-variable-list } ]
... [ { INTO DESCRIPTOR into-sqlda-name | INTO into-host-variable-list ]
... [ ARRAY :nnn } ]

Syntax 2

EXECUTE IMMEDIATE statement

Parameters

• statement-name: – identifier or host-variable
• sqlda-name: – identifier
• into-sqlda-name: – identifier
• statement: – string or host-variable

Examples

• Example 1 – Execute a DELETE:

  EXEC SQL EXECUTE IMMEDIATE
  'DELETE FROM Employees WHERE EmployeeID = 105';

• Example 2 – Execute a prepared DELETE statement:

  EXEC SQL PREPARE del_stmt FROM
  'DELETE FROM Employees WHERE EmployeeID = :a';
  EXEC SQL EXECUTE del_stmt USING :employee_number;

• Example 3 – Execute a prepared query:

  EXEC SQL PREPARE sel1 FROM
  'SELECT Surname FROM Employees WHERE EmployeeID = :a';
  EXEC SQL EXECUTE sel1 USING :employee_number INTO :emp_lname;

Usage

Syntax 1 executes the named dynamic statement that was previously prepared. If the dynamic statement contains host variable placeholders which supply information for the request (bind variables), then either the sqlda-name must specify a C variable which is a pointer to an SQLDA containing enough descriptors for all bind variables occurring in the statement, or the bind variables must be supplied in the host-variable-list.

The optional ARRAY clause can be used with prepared INSERT statements, to allow wide inserts, which insert more than one row at a time and which might improve performance. The value nnn is the number of rows to be inserted. The SQLDA must contain nnn * (columns per row) variables. The first row is placed in SQLDA variables 0 to (columns per row)-1, and so on.

OUTPUT from a SELECT statement or a CALL statement is put either into the variables in the variable list or into the program data areas described by the named SQLDA. The correspondence is one to one from the OUTPUT (selection list or parameters) to either the host variable list or the SQLDA descriptor array.

If EXECUTE is used with an INSERT statement, the inserted row is returned in the second descriptor. For example, when using autoincrement primary keys that generate primary-key values, EXECUTE provides a mechanism to refetch the row immediately and determine the primary-key value assigned to the row.

Syntax 2 is a short form to PREPARE and EXECUTE a statement that does not contain bind variables or output. The SQL statement contained in the string or host variable is immediately executed and is dropped on completion.

EXECUTE can be used for any SQL statement that can be prepared. Cursors are used for SELECT statements or CALL statements that return many rows from the database.

After successful execution of an INSERT, UPDATE, or DELETE statement, the sqlerrd[2] field of the SQLCA (SQLCOUNT) is filled in with the number of rows affected by the operation.

Standards

Permissions

Permissions are checked on the statement being executed.