![]() If I adjust the discount so that it’s lower than the price, it’s inserted successfully. False, addparamFalse) return ctx def Check(constraint): return SQL(CHECK. Here’s what happens if I try to insert a discount that’s larger than the price. 36 I have a table defined by the following SQL: CREATE TABLE test ( id integer PRIMARY KEY NOT NULL UNIQUE, status text NOT NULL, enddate date, / Checks / CHECK (status IN ('Current', 'Complete')) ) I'd like to add a constraint using CHECK that requires enddate to be non-null if the status is 'Complete'. First regex handles acronym followed by word or initial lower-word followed. This table is similar to the first one, except that I’ve added an extra column called Discount.įor the CHECK constraint, I’m now checking that the price is larger than the discount (we don’t want the possibility of having a discount that’s larger than the actual price). Here’s an example of a table-level CHECK constraint. In other words, you can use a table-level constraint to check data from multiple columns. INSERT INTO Products VALUESġ Blue Widget 1.0 Table-Level CHECK ConstraintĪ table-level CHECK constraint checks data across the whole row, rather than just a single column. INSERT INTO Products VALUESīut if I increase it to a value that’s greater than zero, then the INSERT operation succeeds. I get the same result if I try to use a negative value. Result: Error: CHECK constraint failed: Products Now let’s see what happens if we try to insert data that violates this constraint. ![]() In this case, it specifies that the price must be greater than zero. CREATE TABLE Websites ( protocol VARCHAR (255) NOT NULL, domain VARCHAR (255) NOT NULL, path VARCHAR (255) NOT NULL, CONSTRAINT address PRIMARY KEY ( protocol, domain, path ) ) CREATE TABLE Label1 ( protocolre VARCHAR (255) NOT NULL, domainre VARCHAR (255) NOT NULL, pathre VARCHAR (255) NOT NULL, label1 INTEGER CONSTRAINT addre. ![]() The part that goes CHECK (Price > 0) is the CHECK constraint. Here’s an example of creating a column-level CHECK constraint. If a table has a CHECK constraint on it, and you try to insert or update data that violates the CHECK constraint, the operation will fail with an error. In SQLite, you can create a CHECK constraint by adding the applicable code within the CREATE TABLE statement when creating the table. ![]()
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