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## SQLite C Interface

## Virtual Table Constraint Operator Codes

>     #define SQLITE_INDEX_CONSTRAINT_EQ          2
>     #define SQLITE_INDEX_CONSTRAINT_GT          4
>     #define SQLITE_INDEX_CONSTRAINT_LE          8
>     #define SQLITE_INDEX_CONSTRAINT_LT         16
>     #define SQLITE_INDEX_CONSTRAINT_GE         32
>     #define SQLITE_INDEX_CONSTRAINT_MATCH      64
>     #define SQLITE_INDEX_CONSTRAINT_LIKE       65
>     #define SQLITE_INDEX_CONSTRAINT_GLOB       66
>     #define SQLITE_INDEX_CONSTRAINT_REGEXP     67
>     #define SQLITE_INDEX_CONSTRAINT_NE         68
>     #define SQLITE_INDEX_CONSTRAINT_ISNOT      69
>     #define SQLITE_INDEX_CONSTRAINT_ISNOTNULL  70
>     #define SQLITE_INDEX_CONSTRAINT_ISNULL     71
>     #define SQLITE_INDEX_CONSTRAINT_IS         72
>     #define SQLITE_INDEX_CONSTRAINT_LIMIT      73
>     #define SQLITE_INDEX_CONSTRAINT_OFFSET     74
>     #define SQLITE_INDEX_CONSTRAINT_FUNCTION  150

These macros define the allowed values for the sqlite3_index_info.aConstraint[].op field. Each value represents an operator that is part of a constraint term in the WHERE clause of a query that uses a virtual table.

The left-hand operand of the operator is given by the corresponding aConstraint[].iColumn field. An iColumn of -1 indicates the left-hand operand is the rowid. The SQLITE_INDEX_CONSTRAINT_LIMIT and SQLITE_INDEX_CONSTRAINT_OFFSET operators have no left-hand operand, and so for those operators the corresponding aConstraint[].iColumn is meaningless and should not be used.

All operator values from SQLITE_INDEX_CONSTRAINT_FUNCTION through value 255 are reserved to represent functions that are overloaded by the xFindFunction method of the virtual table implementation.

The right-hand operands for each constraint might be accessible using the sqlite3_vtab_rhs_value() interface. Usually the right-hand operand is only available if it appears as a single constant literal in the input SQL. If the right-hand operand is another column or an expression (even a constant expression) or a parameter, then the sqlite3_vtab_rhs_value() probably will not be able to extract it. The SQLITE_INDEX_CONSTRAINT_ISNULL and SQLITE_INDEX_CONSTRAINT_ISNOTNULL operators have no right-hand operand and hence calls to sqlite3_vtab_rhs_value() for those operators will always return SQLITE_NOTFOUND.

The collating sequence to be used for comparison can be found using the sqlite3_vtab_collation() interface. For most real-world virtual tables, the collating sequence of constraints does not matter (for example because the constraints are numeric) and so the sqlite3_vtab_collation() interface is no commonly needed.

See also lists of Objects, Constants, and Functions.