Constraint Conflict Resolution in SQLite In most SQL databases, if you have a UNIQUE, NOT NULL, or CHECK constraint on a table and you try to do an UPDATE or INSERT that violates the constraint, the database will abort the ... 

sqlite3_vtab_collation()

 ... This function returns a pointer to a string that is the name of the appropriate collation sequence to use for text comparisons on the constraint identified by its arguments. The first argument must be the pointer to the sqlite3_index_info object ... 

sqlite3_vtab_in_first(), sqlite3_vtab_in_next()

 ... If the X parameter is not an xFilter argument that was selected for all-at-once IN constraint processing, then these routines return SQLITE_ERROR. Use these routines to access all values on the right-hand side of the IN constraint ... 

SQLITE_INDEX_CONSTRAINT_EQ, SQLITE_INDEX_CONSTRAINT_GT, SQLITE_INDEX_CONSTRAINT_LE, SQLITE_INDEX_CONSTRAINT_LT, SQLITE_INDEX_CONSTRAINT_GE, SQLITE_INDEX_CONSTRAINT_MATCH ... 

 ... 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 not commonly needed. See also lists of Objects, Constants, and Functions.

sqlite3_vtab_rhs_value()

 ... Some constraints, such as SQLITE_INDEX_CONSTRAINT_ISNULL and SQLITE_INDEX_CONSTRAINT_ISNOTNULL, have no right-hand operand. For such constraints, sqlite3_vtab_rhs_value() always returns SQLITE_NOTFOUND. The sqlite3_value object returned in *V is a protected sqlite3_value and remains valid for the duration of the xBestIndex method call ... 

sqlite3_vtab_in()

 ... A constraint on a virtual table of the form "column IN (...)" is communicated to the xBestIndex method as a SQLITE_INDEX_CONSTRAINT_EQ constraint. If xBestIndex wants to use this constraint, it must set the corresponding aConstraintUsage[].argvIndex to a positive integer. Then ... 

 ... SQLITE_SCHEMA, SQLITE_TOOBIG, SQLITE_CONSTRAINT, SQLITE_MISMATCH, SQLITE_MISUSE, SQLITE_NOLFS ... 

Many SQLite functions return an integer result code from the set shown here in order to indicate success or failure. New error codes may be added in future versions of SQLite. See also: extended result code definitions See also lists ... 

 ... The FAIL behavior only works for uniqueness, NOT NULL, and CHECK constraints. A foreign key constraint violation causes an ABORT. IGNORE When an applicable constraint violation occurs, the IGNORE resolution algorithm skips the one row that contains the constraint violation ... 

4.1. Composite Foreign Key Constraints A composite foreign key constraint is one where the child and parent keys are both composite keys. For example, consider the following database schema: CREATE TABLE album( albumartist TEXT, albumname TEXT, albumcover BINARY, PRIMARY KEY(albumartist, albumname) ); CREATE TABLE song ... 

 ... UNIQUE constraints A UNIQUE constraint is similar to a PRIMARY KEY constraint, except that a single table may have any number of UNIQUE constraints. For each UNIQUE constraint on the table, each row must contain a unique combination of values ...