All of the catalog functions have CatalogName and SchemaName (and their associated lengths) on their input argument list. Other input arguments may also include TableName, ProcedureName, or ColumnName (and their associated lengths). These input arguments are used to either identify or constrain the amount of information to be returned. CatalogName, however, must always be a null pointer (with its length set to 0) as DB2 CLI does not support three-part naming.
In the Function Arguments sections for these catalog functions in Chapter 5. "Functions", each of the above input arguments are described either as a pattern-value or just as an ordinary argument. For example, SQLColumnPrivileges() treats SchemaName and TableName as ordinary arguments and ColumnName as a pattern-value.
Inputs treated as ordinary arguments are taken literally and the case of letters is significant. The argument does not qualify a query but rather identifies the information desired. An error results if the application passes a null pointer for this argument.
Inputs treated as pattern-values are used to constrain the size of the result set by including only matching rows as though the underlying query were qualified by a WHERE clause. If the application passes a null pointer for a pattern-value input, the argument is not used to restrict the result set (that is, there is no WHERE clause). If a catalog function has more than one pattern-value input argument, they are treated as though the WHERE clauses in the underlying query were joined by AND; a row appears in this result set only if it meets all the conditions of the WHERE clauses.
Each pattern-value argument can contain:
These argument values are used on conceptual LIKE predicate(s) in the WHERE clause. To treat the metadata characters (_, %) as themselves, an escape character must immediately precede the _ or %. The escape character itself can be specified as part of the pattern by including it twice in succession. An application can determine the escape character by calling SQLGetInfo() with SQL_SEARCH_PATTERN_ESCAPE.