SQLProcedureColumns function (CLI) - Get input/output parameter information for a procedure

The SQLProcedureColumns() function returns a list of input and output parameters that are associated with a stored procedure. The information is returned in an SQL result set, which you can retrieve by using the same functions that you use to process a result set that is generated by a query.

Specification:

  • CLI 2.1
  • ODBC 1.0
Unicode equivalent: You can also use this function with the Unicode character set. The corresponding Unicode function is SQLProcedureColumnsW(). For information about ANSI to Unicode function mappings, see Unicode functions (CLI).

Syntax

SQLRETURN SQLProcedureColumns(
             SQLHSTMT          StatementHandle,   /* hstmt */
             SQLCHAR           *CatalogName,      /* szProcCatalog */
             SQLSMALLINT       NameLength1,       /* cbProcCatalog */
             SQLCHAR           *SchemaName,       /* szProcSchema */
             SQLSMALLINT       NameLength2,       /* cbProcSchema */
             SQLCHAR           *ProcName,         /* szProcName */
             SQLSMALLINT       NameLength3,       /* cbProcName */
             SQLCHAR           *ColumnName,       /* szColumnName */
             SQLSMALLINT       NameLength4);      /* cbColumnName */

Function arguments

Table 1. SQLProcedureColumns arguments
Data type Argument Use Description
SQLHSTMT StatementHandle Input The statement handle.
SQLCHAR * CatalogName Input A catalog qualifier of a 3-part table name. If the target DBMS does not support 3-part naming, and CatalogName is not a null pointer and does not point to a zero-length string, then an empty result set and SQL_SUCCESS is returned. Otherwise, this is a valid filter for DBMSs that supports 3-part naming.
SQLSMALLINT NameLength1 Input The number of SQLCHAR elements (or SQLWCHAR elements for the Unicode variant of this function) that are required to store CatalogName, or SQL_NTS if CatalogName is null-terminated.
SQLCHAR * SchemaName Input A buffer that can contain a pattern value to qualify the result set by schema name.

For Db2® for z/OS®, the stored procedures are in one schema; the only acceptable value for the SchemaName argument is a null pointer. If a value is specified, an empty result set and SQL_SUCCESS are returned. For Db2, SchemaName can contain a valid pattern value. For more information about valid search patterns, see the catalog functions input arguments.

SQLSMALLINT NameLength2 Input The number of SQLCHAR elements (or SQLWCHAR elements for the Unicode variant of this function) that are required to store SchemaName, or SQL_NTS if SchemaName is null-terminated.
SQLCHAR * ProcName Input A buffer that can contain a pattern value to qualify the result set by the procedure name.
SQLSMALLINT NameLength3 Input The number of SQLCHAR elements (or SQLWCHAR elements for the Unicode variant of this function) that are required to store ProcName, or SQL_NTS if ProcName is null-terminated.
SQLCHAR * ColumnName Input A buffer that can contain a pattern value to qualify the result set by the parameter name. Use this argument to further qualify the result set that is already restricted by specifying a non-empty value for ProcName, SchemaName, or both.
SQLSMALLINT NameLength4 Input The number of SQLCHAR elements (or SQLWCHAR elements for the Unicode variant of this function) that are required to store ColumnName, or SQL_NTS if ColumnName is null-terminated.

Usage

The SQLProcedureColumns() function returns the information in a result set, ordered by PROCEDURE_CAT, PROCEDURE_SCHEM, PROCEDURE_NAME, and COLUMN_TYPE. Columns returned by SQLProcedureColumns lists the columns in the result set.

In many cases, calls to the SQLProcedureColumns() function map to a complex and thus expensive query against the system catalog, so you should use the calls sparingly, and save the results rather than repeating calls.

Call SQLGetInfo() with the SQL_MAX_CATALOG_NAME_LEN, SQL_MAX_SCHEMA_NAME_LEN, and SQL_MAX_COLUMN_NAME_LEN to determine the actual lengths of the TABLE_CAT, TABLE_SCHEM, and COLUMN_NAME columns that are supported by the connected DBMS.

If the SQL_ATTR_LONGDATA_COMPAT connection attribute is set, LOB column types are reported as LONG VARCHAR, LONG VARBINARY or LONG VARGRAPHIC types.

Although new columns might be added and the names of the existing columns changed in future releases, the position of the current columns will not change.

If the stored procedure is at a Db2 for z/OS server, the name of the stored procedure must be registered in the SYSIBM.SYSPROCEDURES catalog table of the server. For V8 and later servers, the stored procedures must be registered in the SYSIBM.SYSROUTINES and SYSIBM.SYSPARAMS catalog tables of the server.

For versions of other Db2 servers that do not provide facilities for a stored procedure catalog, an empty result set is returned.

CLI returns information about the input, input/output, and output parameters that are associated with the stored procedure, but cannot return descriptor information for any result sets that the stored procedure might return.

You can specify *ALL as a value in the SchemaName to resolve unqualified stored procedure calls or to find libraries in catalog API calls. CLI searches on all existing schemas in the connected database. You are not required to specify *ALL, as this behavior is the default in CLI. Alternatively, you can set the SchemaFilter IBM® Data Server Driver configuration keyword or the Schema List CLI/ODBC configuration keyword to *ALL.

Columns returned by SQLProcedureColumns
Column 1  PROCEDURE_CAT (VARCHAR(128))
The procedure catalog name. The value is NULL if this procedure does not have catalogs.
Column 2  PROCEDURE_SCHEM (VARCHAR(128))
The name of the schema that contains PROCEDURE_NAME. This is NULL for Db2 for z/OS SQLProcedureColumns() result sets.
Column 3  PROCEDURE_NAME (VARCHAR(128))
The name of the procedure.
Column 4  COLUMN_NAME (VARCHAR(128))
The name of the parameter.
Column 5  COLUMN_TYPE (SMALLINT not NULL)
Identifies the type of information that is associated with this row. The values that can be returned are:
  • SQL_PARAM_INPUT is an input parameter.
  • SQL_PARAM_INPUT_OUTPUT is an input / output parameter.
  • SQL_PARAM_OUTPUT is an output parameter.
The values which are defined in the ODBC specification but are not returned:
  • SQL_PARAM_TYPE_UNKNOWN : the parameter type is unknown.
  • SQL_RETURN_VALUE is the return value of the procedure, in the procedure column.
  • SQL_RESULT_COL is a column in the result set.
Column 6  DATA_TYPE (SMALLINT not NULL)
The SQL data type.
Column 7  TYPE_NAME (VARCHAR(128) not NULL)
The character string that represents the name of the data type that corresponds to DATA_TYPE.
Column 8  COLUMN_SIZE (INTEGER)
For XML arguments in SQL routines, zero is returned (as XML arguments have no length). For cataloged external routines, however, XML parameters are declared as XML AS CLOB(n), in which case COLUMN_SIZE is the cataloged length, n.

If the DATA_TYPE column value denotes a character or binary string, this column contains the maximum length in SQLCHAR or SQLWCHAR elements. If DATA_TYPE column value is a graphic (DBCS) string, the COLUMN_SIZE is the number of double byte SQLCHAR or SQLWCHAR elements for the parameter.

For date, time, and timestamp data types, this is the total number of SQLCHAR or SQLWCHAR elements that are required to display the value when converted to character data type.

For the columns that are defined with the CODEUNITS32 unit, the number of code units for the column is returned.

For numeric data types, COLUMN_SIZE value is either the total number of digits or the total number of bits that are allowed in the column, depending on the value in the NUM_PREC_RADIX column in the result set.

See the table of data type precision.

Column 9  BUFFER_LENGTH (INTEGER)
The maximum number of bytes for the associated C buffer to store data from this parameter if SQL_C_DEFAULT is specified on the SQLBindCol(), SQLGetData() and SQLBindParameter() calls. This length excludes any null-terminator. For exact numeric data types, the length accounts for the decimal and the sign.

For XML arguments in SQL routines, zero is returned (as XML arguments have no length). For cataloged external routines, however, XML parameters are declared as XML AS CLOB(n), in which case BUFFER_LENGTH is the cataloged length, n.

See the table of data type length.

Column 10  DECIMAL_DIGITS (SMALLINT)
The scale of the parameter. NULL is returned for data types where scale is not applicable.

See the table of data type scale.

Column 11  NUM_PREC_RADIX (SMALLINT)
Either 10, 2, or NULL. If DATA_TYPE is an approximate numeric data type, this column contains the value 2, and the COLUMN_SIZE column contains the number of bits that are allowed in the parameter.

If DATA_TYPE is an exact numeric data type, this column contains the value 10, and the COLUMN_SIZE and DECIMAL_DIGITS columns contain the number of decimal digits that are allowed for the parameter.

For numeric data types, the DBMS can return a NUM_PREC_RADIX of either 10 or 2.

NULL is returned for data types where radix is not applicable.

Column 12  NULLABLE (SMALLINT not NULL)
SQL_NO_NULLS if the parameter does not accept NULL values.

SQL_NULLABLE if the parameter accepts NULL values.

Column 13  REMARKS (VARCHAR(254))
Might contain descriptive information about the parameter.
Column 14  COLUMN_DEF (VARCHAR)
The default value of the column.

If NULL was specified as the default value, this column is the word NULL, not enclosed in quotation marks. If the default value cannot be represented without truncation, this column contains TRUNCATED, not enclosed in single quotation marks. If no default value is specified, this column is NULL.

You can use the value of COLUMN_DEF to generate a new column definition, except when COLUMN_DEF contains the value TRUNCATED.

Column 15  SQL_DATA_TYPE (SMALLINT not NULL)
The value of the SQL data type as it is displayed in the SQL_DESC_TYPE field of the descriptor. This column is the same as the DATA_TYPE column except for datetime data types (CLI does not support interval data types).

For datetime data types, the SQL_DATA_TYPE field in the result set is SQL_DATETIME, and the SQL_DATETIME_SUB field returns the subcode for the specific datetime data type (SQL_CODE_DATE, SQL_CODE_TIME or SQL_CODE_TIMESTAMP).

Column 16  SQL_DATETIME_SUB (SMALLINT)
The subtype code for datetime data types. For all other data types this column returns a NULL value (including interval data types that CLI does not support).
Column 17  CHAR_OCTET_LENGTH (INTEGER)
The maximum length, in bytes, of a character data type column including those that are defined as CODEUNITS32. For all other data types, this column returns a NULL.
Column 18  ORDINAL_POSITION (INTEGER NOT NULL)
Contains the ordinal position of the parameter that is given by COLUMN_NAME in this result set. This is the ordinal position of the argument to be provided on the CALL statement. The leftmost argument has an ordinal position of 1.
Column 19  IS_NULLABLE (Varchar)
  • "NO" if the column cannot contain NULLs.
  • "YES" if the column can include NULLs.
  • Zero-length string if nullability is unknown.
ISO rules are followed to determine nullability.

An ISO SQL-compliant DBMS cannot return an empty string.

The value that is returned for this column is different than the value that is returned for the NULLABLE column. (See the description of the NULLABLE column.)

Note:
  • The column names that are used by CLI follow the X/Open CLI CAE specification style. The column types, contents, and order are identical to those defined for the SQLProcedureColumns() result set in ODBC.
  • If two modules contain procedures that share the same name, SQLProcedureColumns() returns details about both procedures.

Return codes

  • SQL_ERROR
  • SQL_INVALID_HANDLE
  • SQL_STILL_EXECUTING
  • SQL_SUCCESS
  • SQL_SUCCESS_WITH_INFO

Diagnostics

Table 2. SQLProcedureColumns SQLSTATEs
SQLSTATE Description Explanation
24000 Invalid cursor state. A cursor was already opened on the statement handle.
40003 08S01 Communication link failure. The communication link between the application and data source failed before the function completed.
42601 PARMLIST syntax error. The PARMLIST value in the stored procedures catalog table contains a syntax error.
HY001 Memory allocation failure. Db2 CLI is unable to allocate memory required to support execution or completion of the function. It is likely that process-level memory has been exhausted for the application process. Consult the operating system configuration for information about process-level memory limitations.
HY008 Operation was Canceled. Asynchronous processing was enabled for StatementHandle. The function was called and before it completed execution, SQLCancel() was called on StatementHandle from a different thread in a multithreaded application. Then the function was called again on StatementHandle.
HY010 Function sequence error.

The function was called while in a data-at-execute (SQLParamData(), SQLPutData()) operation.

The function was called while in a BEGIN COMPOUND and END COMPOUND SQL operation.

An asynchronously executing function (not this one) was called for the StatementHandle and was still executing when this function was called.

The function was called before a statement was prepared on the statement handle.
HY014 No more handles. Db2 CLI was unable to allocate a handle due to resource limitations.
HY090 Invalid string or buffer length. The value of one of the name-length arguments was less than 0, but not equal to SQL_NTS.
HYT00 Timeout expired. The timeout period expired before the data source returned the result set. You can set the timeout period by using the SQL_ATTR_QUERY_TIMEOUT attribute for SQLSetStmtAttr().
Note: This SQLSTATE applies only to .Net applications.

Restrictions

The SQLProcedureColumns() function does not return information about the attributes of result sets that might be returned from stored procedures.

If an application is connected to a Db2 server that does not provide support for a stored procedure catalog, or does not provide support for stored procedures, the SQLProcedureColumns() function returns an empty result set.

Example

The following code example gets parameter information for a procedure. 
  /* get input/output parameter information for a procedure */
  sqlrc = SQLProcedureColumns(hstmt,
                              NULL,
                              0, /* catalog name not used */
                              (unsigned char *)colSchemaNamePattern,
                              SQL_NTS, /* schema name not currently used */
                              (unsigned char *)procname,
                              SQL_NTS,
                              colNamePattern,
                              SQL_NTS); /* all columns */