Computes a SqlExpr expression which can be used in the WHERE clause of an UPDATE or DELETE
statement when a row from the result of the stsel statement has to be modified.
If require_pk is true then this function will return a non null
SqlExpr only if it can use a primary key of mtable. If require_pk
is false, then it will try to use a primary key of mtable, and if none is
available, it will use all the columns of mtable to compute a condition statement.
| cnc |
a Connection, or null |
| stsel |
a |
| mtable | |
| require_pk |
set to true if a primary key is required |
|
a new SqlExpr, or null if an error occurred. |