SIGNAL statement

See SIGNAL for details.

Description

label

Specifies the label for the SIGNAL statement. The label name cannot be the same as the routine name or another label within the same scope. For more information, see References to SQL labels.

SQLSTATE VALUE

Specifies the SQLSTATE that will be signalled. The specified value must not be null and must follow the rules for SQLSTATEs:

• Each character must be from the set of digits ('0' through '9') or non-accented upper case letters ('A' through 'Z').
• The SQLSTATE class (first two characters) cannot be '00' since this represents successful completion.

If the SQLSTATE does not conform to these rules, an error is returned.

sqlstate-string-constant

The sqlstate-string-constant must be a character string constant with exactly 5 characters.

sqlstate-string-variable

The sqlstate-string-variable must be a character or Unicode graphic variable. The actual length of the contents of the variable must be 5.

SQL-condition-name

Specifies the name of the condition that will be signalled. The SQL-condition-name must be declared within the compound-statement.

SET

Introduces the assignment of values to condition-information-items. The condition-information-item values can be accessed using the GET DIAGNOSTICS statement. The only condition-information-item that can be accessed in the SQLCA is MESSAGE_TEXT.

MESSAGE_TEXT

Specifies a string that describes the error or warning.

If an SQLCA is used,

• the string is returned in the SQLERRMC field of the SQLCA
• if the actual length of the string is longer than 1000 bytes, it is truncated without a warning.

CONSTRAINT_CATALOG

Specifies a string that indicates the name of the database that contains a constraint related to the signalled error or warning.

CONSTRAINT_SCHEMA

Specifies a string that indicates the name of the schema that contains a constraint related to the signalled error or warning.

CONSTRAINT_NAME

Specifies a string that indicates the name of a constraint related to the signalled error or warning.

CATALOG_NAME

Specifies a string that indicates the name of the database that contains a table or view related to the signalled error or warning.

SCHEMA_NAME

Specifies a string that indicates the name of the schema that contains a table or view related to the signalled error or warning.

TABLE_NAME

Specifies a string that indicates the name of a table or view related to the signalled error or warning.

COLUMN_NAME

Specifies a string that indicates the name of a column in the table or view related to the signalled error or warning.

CURSOR_NAME

Specifies a string that indicates the name of a cursor related to the signalled error or warning.

CLASS_ORIGIN

Specifies a string that indicates the origin of the SQLSTATE class related to the signalled error or warning.

SUBCLASS_ORIGIN

Specifies a string that indicates the origin of the SQLSTATE subclass related to the signalled error or warning.

SQL-variable-name

Identifies an SQL variable declared within the compound-statement, that contains the value to be assigned to the condition-information-item. The SQL variable must be defined as CHAR, VARCHAR, Unicode GRAPHIC, or Unicode VARGRAPHIC variable.

SQL-parameter-name

Identifies an SQL parameter declared within the compound-statement, that contains the value to be assigned to the condition-information-item. The SQL parameter must be defined as CHAR, VARCHAR, Unicode GRAPHIC, or Unicode VARGRAPHIC variable.

diagnostic-string-constant

Specifies a character string constant that contains the value to be assigned to the condition-information-item.

( diagnostic-string-constant )

Specifies a character string constant that contains the message text.

This form is only allowed in the triggered action of a CREATE TRIGGER statement.

To conform with the ANS and ISO standards, this form should not be used. It is provided for compatibility with other products.

Notes

SQLSTATE values: Any valid SQLSTATE value can be used in the SIGNAL statement. However, it is recommended that programmers define new SQLSTATEs based on ranges reserved for applications. This prevents the unintentional use of an SQLSTATE value that might be defined by the database manager in a future release.

For more information about SQLSTATEs, see the SQL Messages and Codes topic collection.

Assignment: When the SIGNAL statement is executed, the value of each of the specified string-constants and variables is assigned to the corresponding condition-information-item. However, if the length of a string-constant or variable is longer than the maximum length of the corresponding condition-information-item, it is truncated without a warning. For details on the assignment rules, see Assignments and comparisons. For details on the maximum length of specific condition-information-items, see GET DIAGNOSTICS.

Processing a SIGNAL statement: When a SIGNAL statement is issued, the SQLCODE returned in the SQLCA is based on the SQLSTATE value as follows:

• If the specified SQLSTATE class is either '01' or '02', a warning or not found is signalled and the SQLCODE is set to +438.
• Otherwise, an exception is signalled and the SQLCODE is set to –438.

If the SQLSTATE or condition indicates that an exception (SQLSTATE class other than '01' or '02') is signalled,

• If a handler exists in the same compound statement as the SIGNAL statement, and the compound statement contains a handler for SQLEXCEPTION or the specified SQLSTATE or condition; the exception is handled and control is transferred to that handler.
• If the compound-statement is nested and an outer level compound-statement has a handler for SQLEXCEPTION or the specified SQLSTATE or condition; the exception is handled and control is transferred to that handler.
• Otherwise, the exception is not handled and control is immediately returned to the end of the compound statement.

If the SQLSTATE or condition indicates that a warning (SQLSTATE class '01') or not found (SQLSTATE class '02') is signalled,

• If a handler exists in the same compound statement as the SIGNAL statement, and the compound statement contains a handler for SQLWARNING (if the SQLSTATE class is '01'), NOT FOUND (if the SQLSTATE class is '02'), or the specified SQLSTATE or condition; the warning or not found condition is handled and control is transferred to that handler.
• If the compound-statement is nested and an outer level compound statement contains a handler for SQLWARNING (if the SQLSTATE class is '01'), NOT FOUND (if the SQLSTATE class is '02'), or the specified SQLSTATE or condition; the warning or not found condition is not handled and processing continues with the next statement.
• Otherwise, the warning is not handled and processing continues with the next statement.

Considerations for the diagnostics area: The SIGNAL statement starts with a clear of the diagnostics area and then sets the RETURNED_SQLSTATE to reflect the specified SQLSTATE or SQL-condition-name. If any signal-information is specified, the corresponding items in the condition area are assigned the specified values. DB2_RETURNED_SQLCODE is set to +438 or -438 corresponding to the specified SQLSTATE or SQL-condition-name.

Example

An SQL procedure for an order system that signals an application error when a customer number is not known to the application. The ORDERS table includes a foreign key to the CUSTOMER table, requiring that the CUSTNO exist before an order can be inserted.