What is the default constraint in SQL?

What is the default constraint in SQL?

The DEFAULT Constraint is used to fill a column with a default and fixed value. The value will be added to all new records when no other value is provided.

How do you write a default constraint?

Steps for a Default Constraint

1. Creation of Default Constraint with Create Query or the Alter Query. Using the Create Query. Syntax: CREATE TABLE Persons ( col1 datatype,
2. Drop the Default Constraint. Syntax: ALTER TABLE tableName. ALTER colName DROP DEFAULT; ALTER TABLE tableName ALTER colName DROP DEFAULT;

How do I set default value in SQL?

Use SSMS to specify a default

1. In Object Explorer, right-click the table with columns for which you want to change the scale and select Design.
2. Select the column for which you want to specify a default value.
3. In the Column Properties tab, enter the new default value in the Default Value or Binding property.

How does order by work in SQL?

The ORDER BY statement in SQL is used to sort the fetched data in either ascending or descending according to one or more columns.

1. By default ORDER BY sorts the data in ascending order.
2. We can use the keyword DESC to sort the data in descending order and the keyword ASC to sort in ascending order.

How do I add a default constraint to an existing table in SQL?

The correct way to do this is as follows:

1. Run the command: sp_help [table name]
2. Copy the name of the CONSTRAINT .
3. Drop the DEFAULT CONSTRAINT : ALTER TABLE [table name] DROP [NAME OF CONSTRAINT]
4. Run the command below: ALTER TABLE [table name] ADD DEFAULT [DEFAULT VALUE] FOR [NAME OF COLUMN]

Is index a constraint in SQL?

Is an index a constraint? Not really, but a unique index has the same effect as a unique constraint on the same columns. So, you can think of a unique index as implementing a unique constraint.

What is order by 4 in SQL?

You also may notice that the number 4 is specified in the order by clause. The number 4 specifies the position of the columns in the SQL query. In this case, position of BusinessEntityID is 1, FirstName is 2, MiddleName is 3 and LastName is 4.

WHERE does order by Go in SQL?

Note: SQL ORDER BY clause always come at the end of a SELECT statement. Name of the table. Name of the columns of the table.

What are different types of constraints?

Types of Constraints in DBMS-

• Domain constraint.
• Tuple Uniqueness constraint.
• Key constraint.
• Entity Integrity constraint.
• Referential Integrity constraint.