What is metadata in SQL database?
Metadata, as most of you may already know, provides the basic and relevant information about the data. Metadata functions in SQL Server return information about the database, database objects, database files, file groups etc. in SQL Server.
What is check constraint in database?
A check constraint is a type of integrity constraint in SQL which specifies a requirement that must be met by each row in a database table. It can refer to a single column, or multiple columns of the table. The result of the predicate can be either TRUE , FALSE , or UNKNOWN , depending on the presence of NULLs.
What is constraint in SQL with example?
The following constraints are commonly used in SQL:
- NOT NULL – Ensures that a column cannot have a NULL value.
- UNIQUE – Ensures that all values in a column are different.
- PRIMARY KEY – A combination of a NOT NULL and UNIQUE .
- FOREIGN KEY – Prevents actions that would destroy links between tables.
What is metadata in SQL example?
Usually, the metadata returns the information about the database, db objects, db files, etc., in the SQL server. It also consists of information regarding the views, procedures, functions, and triggers. Access to this metadata is provided in the form of a set of tables or views called system catalog or data dictionary.
How can check constraint in SQL query?
The syntax for enabling a check constraint in SQL Server (Transact-SQL) is: ALTER TABLE table_name WITH CHECK CHECK CONSTRAINT constraint_name; table_name. The name of the table that you wish to enable the check constraint.
What does check constraint do in SQL?
The CHECK constraint is used to limit the value range that can be placed in a column. If you define a CHECK constraint on a column it will allow only certain values for this column. If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other columns in the row.
How do I find constraints on a table in SQL?
What is constraints in SQL and how many constraints are in SQL?
SQL Constraints are rules used to limit the type of data that can go into a table, to maintain the accuracy and integrity of the data inside table. Constraints can be divided into the following two types, Column level constraints: Limits only column data. Table level constraints: Limits whole table data.