SQLForeignKeys
Conformance
Version Introduced: ODBC 1.0
Standards Compliance: ODBC
Summary
SQLForeignKeys can return:
A list of foreign keys in the specified table (columns in the specified table
that refer to primary keys in other tables).
A list of foreign keys in other tables that refer to the primary key in the
specified table.
The driver returns each list as a result set on the specified statement.
Syntax
SQLRETURN SQLForeignKeys(
SQLHSTMT StatementHandle,
SQLCHAR * PKCatalogName,
SQLSMALLINT NameLength1,
SQLCHAR * PKSchemaName,
SQLSMALLINT NameLength2,
SQLCHAR * PKTableName,
SQLSMALLINT NameLength3,
SQLCHAR * FKCatalogName,
SQLSMALLINT NameLength4,
SQLCHAR * FKSchemaName,
SQLSMALLINT NameLength5,
SQLCHAR * FKTableName,
SQLSMALLINT NameLength6);
Arguments
StatementHandle [Input]
Statement handle.
PKCatalogName [Input]
Primary key table catalog name. If a driver supports catalogs for some tables
but not for others, such as when the driver retrieves data from different DBMSs, an empty string
("") denotes those tables that do not have catalogs. PKCatalogName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, PKCatalogName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, PKCatalogName is an ordinary argument; it is treated literally, and its case is
significant. For more information, see “Arguments in Catalog Functions” in Chapter 7, “Catalog Functions.”
NameLength1 [Input]
Length of *PKCatalogName, in bytes.
PKSchemaName [Input]
Primary key table schema name. If a driver supports schemas for some tables
but not for others, such as when the driver retrieves data from different DBMSs,
an empty string ("") denotes those tables that do not have schemas. PKSchemaName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, PKSchemaName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, PKSchemaName is an ordinary argument; it is treated literally, and its case is significant.
NameLength2 [Input]
Length of *PKSchemaName, in bytes.
PKTableName [Input]
Primary key table name. PKTableName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, PKTableName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, PKTableName is an ordinary argument; it is treated literally, and its case is significant.
NameLength3 [Input]
Length of *PKTableName.
FKCatalogName [Input]
Foreign key table catalog name. If a driver supports catalogs for some tables
but not for others, such as when the driver retrieves data from different
DBMSs, an empty string ("") denotes those tables that do not have catalogs. FKCatalogName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, FKCatalogName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, FKCatalogName is an ordinary argument; is treated literally, and its case is significant.
NameLength4 [Input]
Length of *FKCatalogName.
FKSchemaName [Input]
Foreign key table schema name. If a driver supports schemas for some tables
but not for others, such as when the driver retrieves data from different DBMSs,
an empty string ("") denotes those tables that do not have schemas. FKSchemaName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, FKSchemaName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, FKSchemaName is an ordinary argument; it is treated literally, and its case is significant.
NameLength5 [Input]
Length of *FKSchemaName.
FKTableName [Input]
Foreign key table name. FKTableName cannot contain a string search pattern.
If the SQL_ATTR_METADATA_ID statement attribute is set to SQL_TRUE, FKTableName is treated as an identifier, and its case is not significant. If it is
SQL_FALSE, FKTableName is an ordinary argument; it is treated literally, and its case is significant.
NameLength6 [Input]
Length of *FKTableName.
Returns
SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_STILL_EXECUTING, SQL_ERROR, or
SQL_INVALID_HANDLE.
Diagnostics
When SQLForeignKeys returns SQL_ERROR or SQL_SUCCESS_WITH_INFO, an associated SQLSTATE value may
be obtained by calling SQLGetDiagRec with a HandleType of SQL_HANDLE_STMT and a Handle of StatementHandle. The following table lists the SQLSTATE values commonly returned by SQLForeignKeys and explains each one in the context of this function; the notation “(DM)”
precedes the descriptions of SQLSTATEs returned by the Driver Manager. The return
code associated with each SQLSTATE value is SQL_ERROR, unless noted otherwise.
01000
| General warning
| Driver-specific informational message. (Function returns
SQL_SUCCESS_WITH_INFO.)
|
08S01
| Communication link failure
| The communication link between the driver and the data source to which the
driver was connected failed before the function completed processing.
|
24000
| Invalid cursor state
| A cursor was open on the StatementHandle and SQLFetch or SQLFetchScroll had been called. This error is returned by the Driver Manager if SQLFetch or SQLFetchScroll has not returned SQL_NO_DATA, and is returned by the driver if SQLFetch or SQLFetchScroll has returned SQL_NO_DATA.
A cursor was open on the StatementHandle but SQLFetch or SQLFetchScroll had not been called.
|
40001
| Serialization failure
| The transaction was rolled back due to a resource deadlock with another
transaction.
|
40003
| Statement completion unknown
| The associated connection failed during the execution of this function and the
state of the transaction cannot be determined.
|
HY000
| General error
| An error occurred for which there was no specific SQLSTATE and for which no
implementation-specific SQLSTATE was defined. The error message returned by SQLGetDiagRec in the *MessageText buffer describes the error and its cause.
|
HY001
| Memory allocation error
| The driver was unable to allocate memory required to support execution or
completion of the function.
|
HY008
| Operation canceled
| Asynchronous processing was enabled for the StatementHandle. The function was called and before it completed execution, SQLCancel was called on the StatementHandle. Then the function was called again on the StatementHandle.
The function was called and, before it completed execution, SQLCancel was called on the StatementHandle from a different thread in a multithread application.
|
HY009
| Invalid use of null pointer
| (DM) The arguments PKTableName and FKTableName were both null pointers.
(DM) The SQL_ATTR_METADATA_ID statement attribute was set to SQL_TRUE, the FKCatalogName or PKCatalogName argument was a null pointer, and the SQL_CATALOG_NAME InfoType returns that catalog names are supported.
(DM) The SQL_ATTR_METADATA_ID statement attribute was set to SQL_TRUE, and the FKSchemaName, PKSchemaName, FKTableName, or PKTableName argument was a null pointer.
|
HY010
| Function sequence error
| (DM) An asynchronously executing function (not this one) was called for the StatementHandle and was still executing when this function was called.
(DM) SQLExecute, SQLExecDirect, SQLBulkOperations, or SQLSetPos was called for the StatementHandle and returned SQL_NEED_DATA. This function was called before data was sent for
all data-at-execution parameters or columns.
|
HY013
| Memory management error
| The function call could not be processed because the underlying memory objects
could not be accessed, possibly because of low memory conditions.
|
HY090
| Invalid string or buffer length
| (DM) The value of one of the name length arguments was less than 0, but not
equal to SQL_NTS.
|
|
| The value of one of the name length arguments exceeded the maximum length
value for the corresponding name (see “Comments”).
|
HYC00
| Optional feature not implemented
| A catalog name was specified and the driver or data source does not support
catalogs.
A schema name was specified and the driver or data source does not support
schemas.
|
|
| The combination of the current settings of the SQL_ATTR_CONCURRENCY and
SQL_ATTR_CURSOR_TYPE statement attributes was not supported by the driver or data
source.
The SQL_ATTR_USE_BOOKMARKS statement attribute was set to SQL_UB_VARIABLE, and
the SQL_ATTR_CURSOR_TYPE statement attribute was set to a cursor type for
which the driver does not support bookmarks.
|
HYT00
| Timeout expired
| The query timeout period expired before the data source returned the result
set. The timeout period is set through SQLSetStmtAttr, SQL_ATTR_QUERY_TIMEOUT.
|
HYT01
| Connection timeout expired
| The connection timeout period expired before the data source responded to the
request. The connection timeout period is set through SQLSetConnectAttr, SQL_ATTR_CONNECTION_TIMEOUT.
|
IM001
| Driver does not support this function
| (DM) The driver associated with the StatementHandle does not support the function.
|
Comments
For information how about the information returned by this function might be
used, see “Uses of Catalog Data” in Chapter 7, “Catalog Functions.”
If *PKTableName contains a table name, SQLForeignKeys returns a result set containing the primary key of the specified table and
all of the foreign keys that refer to it. The list of foreign keys in other
tables does not include foreign keys that point to unique constraints in the
specified table.
If *FKTableName contains a table name, SQLForeignKeys returns a result set containing all of the foreign keys in the specified
table that point to primary keys in others tables, and the primary keys in the
other tables to which they refer. The list of foreign keys in the specified table
does not contain foreign keys that refer to unique constraints in other tables.
If both *PKTableName and *FKTableName contain table names, SQLForeignKeys returns the foreign keys in the table specified in *FKTableName that refer to the primary key of the table specified in *PKTableName. This should be one key at most.
Note For more information about the general use, arguments, and returned data of
ODBC catalog functions, see Chapter 7, “Catalog Functions.”
SQLForeignKeys returns results as a standard result set. If the foreign keys associated with
a primary key are requested, the result set is ordered by FKTABLE_CAT,
FKTABLE_SCHEM, FKTABLE_NAME, and KEY_SEQ. If the primary keys associated with a
foreign key are requested, the result set is ordered by PKTABLE_CAT, PKTABLE_SCHEM,
PKTABLE_NAME, and KEY_SEQ. The following table lists the columns in the result
set.
The lengths of VARCHAR columns are not shown in the table; the actual lengths
depend on the data source. To determine the actual lengths of the PKTABLE_CAT
or FKTABLE_CAT, PKTABLE_SCHEM or FKTABLE_SCHEM, PKTABLE_NAME or FKTABLE_NAME,
and PKCOLUMN_NAME or FKCOLUMN_NAME columns, an application can call SQLGetInfo with the SQL_MAX_CATALOG_NAME_LEN, SQL_MAX_SCHEMA_NAME_LEN,
SQL_MAX_TABLE_NAME_LEN, and SQL_MAX_COLUMN_NAME_LEN options.
The following columns have been renamed for ODBC 3.0. The column name changes
do not affect backward compatibility because applications bind by column number.
#define TAB_LEN SQL_MAX_TABLE_NAME_LEN + 1
#define COL_LEN SQL_MAX_COLUMN_NAME_LEN + 1
LPSTR szTable; /* Table to display */
UCHAR szPkTable[TAB_LEN]; /* Primary key table name */
UCHAR szFkTable[TAB_LEN]; /* Foreign key table name */
UCHAR szPkCol[COL_LEN]; /* Primary key column */
UCHAR szFkCol[COL_LEN]; /* Foreign key column */
SQLHSTMT hstmt;
SQLINTEGER cbPkTable, cbPkCol, cbFkTable, cbFkCol, cbKeySeq;
SQLSMALLINT iKeySeq;
SQLRETURN retcode;
/* Bind the columns that describe the primary and foreign keys. */
/* Ignore the table schema, name, and catalog for this example. */
SQLBindCol(hstmt, 3, SQL_C_CHAR, szPkTable, TAB_LEN, &cbPkTable);
SQLBindCol(hstmt, 4, SQL_C_CHAR, szPkCol, COL_LEN, &cbPkCol);
SQLBindCol(hstmt, 5, SQL_C_SSHORT, &iKeySeq, TAB_LEN, &cbKeySeq);
SQLBindCol(hstmt, 7, SQL_C_CHAR, szFkTable, TAB_LEN, &cbFkTable);
SQLBindCol(hstmt, 8, SQL_C_CHAR, szFkCol, COL_LEN, &cbFkCol);
strcpy(szTable, "ORDERS");
/* Get the names of the columns in the primary key. */
retcode = SQLPrimaryKeys(hstmt,
NULL, 0, /* Catalog name */
NULL, 0, /* Schema name */
szTable, SQL_NTS); /* Table name */
while ((retcode == SQL_SUCCESS) || (retcode == SQL SUCCESS_WITH_INFO)) {
/* Fetch and display the result set. This will be a list of the */
/* columns in the primary key of the ORDERS table. */
retcode = SQLFetch(hstmt);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
fprintf(out, "Table: %s Column: %s Key Seq: %hd \n", szPkTable, szPkCol,
iKeySeq);
}
/* Close the cursor (the hstmt is still allocated). */
SQLFreeStmt(hstmt, SQL_CLOSE);
/* Get all the foreign keys that refer to ORDERS primary key.*/
retcode = SQLForeignKeys(hstmt,
NULL, 0, /* Primary catalog */
NULL, 0, /* Primary schema */
szTable, SQL_NTS, /* Primary table */
NULL, 0, /* Foreign catalog*/
NULL, 0, /* Foreign schema */
NULL, 0); /* Foreign table */
while ((retcode == SQL_SUCCESS) || (retcode == SQL_SUCCESS_WITH_INFO)) {
/* Fetch and display the result set. This will be all of the */
/* foreign keys in other tables that refer to the ORDERS */
/* primary key. */
retcode = SQLFetch(hstmt);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
fprintf(out, "%-s ( %-s ) <-- %-s ( %-s )\n", szPkTable,
szPkCol, szFkTable, szFkCol);
}
/* Close the cursor (the hstmt is still allocated). */
SQLFreeStmt(hstmt, SQL_CLOSE);
/* Get all the foreign keys in the ORDERS table. */
retcode = SQLForeignKeys(hstmt,
NULL, 0, /* Primary catalog */
NULL, 0, /* Primary schema */
NULL, 0, /* Primary table */
NULL, 0, /* Foreign catalog */
NULL, 0, /* Foreign schema */
szTable, SQL_NTS); /* Foreign table */
while ((retcode == SQL_SUCCESS) || (retcode == SQL_SUCCESS_WITH_INFO)) {
/* Fetch and display the result set. This will be all of the */
/* primary keys in other tables that are referred to by foreign */
/* keys in the ORDERS table. */
retcode = SQLFetch(hstmt);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
fprintf(out, "%-s ( %-s )--> %-s ( %-s )\n", szFkTable,
szFkCol, szPkTable, szPkCol);
}
/* Free the hstmt. */
SQLFreeStmt(hstmt, SQL_DROP);