In SQL Server, we can query the sys.default_constraints system catalog view to return a list of DEFAULT constraints in the current database.
Tag: constraints
Return All CHECK Constraints in a SQL Server Database (T-SQL)
In SQL Server, we can query the sys.check_constraints system catalog view to return a list of CHECK constraints in the current database.
How to Drop a DEFAULT Constraint in SQL Server
In SQL Server, we can drop DEFAULT constraints by using the ALTER TABLE statement with the DROP CONSTRAINT argument.
Set a Default Value for a Column in SQLite: DEFAULT Constraint
When creating a table in SQLite, you have the option of adding constraints to each column.
One such constraint is the DEFAULT constraint.
The DEFAULT constraint allows you to specify a value to be used in the event no value is supplied for that column when a new row is inserted.
If you don’t use a DEFAULT clause, then the default value for a column is NULL.
How to Skip Rows that Violate Constraints When Inserting Data in SQLite
In SQLite, when you try to insert multiple rows into a table, and any of those rows violates a constraint on that table, the operation will fail.
This is to be expected, after all, that’s what the constraint is for.
But what if you just want to ignore any rows that violate constraints? In other words, if a row violates a constraint, you want SQLite to skip that row, then carry on processing the next row, and so on.
Fortunately, there’s an easy way to do this in SQLite.
Continue readingHow to Enable/Disable CHECK Constraints in SQLite
If you ever need to enable or disable all CHECK constraints in SQLite, you can use the ignore_check_constraints PRAGMA statement.
This pragma statement explicitly enables or disables the enforcement of CHECK constraints. The default setting is off, meaning that CHECK constraints are enforced by default.
What is a CHECK Constraint?
In database terms, a CHECK constraint is a type of constraint that checks data before it enters the database.
CHECK constraints help maintain data integrity, because they prevent invalid data entering the database.
Continue readingCreate a CHECK Constraint in SQLite
In SQLite, you can create a CHECK constraint by adding the applicable code within the CREATE TABLE statement when creating the table.
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.
Return All Disabled Constraints in SQL Server (T-SQL Example)
Here’s some T-SQL code you can use to get a list of all CHECK and foreign key constraints in a SQL Server database.
See if a Table has a DEFAULT Constraint in SQL Server using OBJECTPROPERTY()
You can use the OBJECTPROPERTY() function in SQL Server to see whether or not a table has a DEFAULT constraint.
To do this, pass the table’s object ID as the first argument, and TableHasDefaultCnst as the second argument. The function returns a 1 or a 0 depending on whether or not it has a DEFAULT constraint.
A return value of 1 means that the table has a DEFAULT constraint, and a value of 0 means that it’s not.