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14 paź 2008 · SELECT CONSTRAINT_NAME, TABLE_NAME, REFERENCED_TABLE_NAME FROM information_schema.REFERENTIAL_CONSTRAINTS WHERE CONSTRAINT_SCHEMA = '<schema>' AND TABLE_NAME = '<table>' for foreign keys from <table>, or
19 mar 2019 · This will travel the hierarchy of foreign keys for a given table and column and return columns from child and grandchild, and all descendant tables. It uses sub-queries to add r_table_name and r_column_name to user_constraints, and then uses them to connect rows.
You can add a foreign key constraint to an existing table using the following ALTER TABLE syntax: ALTER TABLE tbl_name ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (col_name, ...) REFERENCES tbl_name (col_name,...) [ON DELETE reference_option] [ON UPDATE reference_option]
19 sie 2024 · For example, let’s use the INFORMATION_SCHEMA views to list the foreign keys for the Registration table: SELECT FK.TABLE_NAME AS foreign_key_table, CU.COLUMN_NAME AS foreign_key_column, PK.TABLE_NAME AS referenced_table, PT.COLUMN_NAME AS referenced_column, C.CONSTRAINT_NAME AS constraint_name FROM INFORMATION_SCHEMA.
To allow naming of a FOREIGN KEY constraint, and for defining a FOREIGN KEY constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Orders
23 maj 2017 · LEFT JOIN USER_CONSTRAINTS CONS_R ON CONS_R.CONSTRAINT_NAME = CONS.R_CONSTRAINT_NAME. LEFT JOIN USER_CONS_COLUMNS COLS_R ON COLS_R.CONSTRAINT_NAME = CONS.R_CONSTRAINT_NAME. -- returns only foreign key constraints. WHERE CONS.CONSTRAINT_TYPE = 'R'.
3.6.6 Using Foreign Keys. In MySQL, InnoDB tables support checking of foreign key constraints. See Chapter 15, The InnoDB Storage Engine, and Section 1.7.2.3, “FOREIGN KEY Constraint Differences”. A foreign key constraint is not required merely to join two tables.
