#Sql server create table how to

The condition written in the CHECK is quite similar in its structure to each of the conditions written in a WHERE statement.

The syntax for defining a Check Constraint is as follows:Д¬olumn_name column_DataType CHECK (Condition), In SQL Server, the Check constraint defines a condition that each row must satisfy. The syntax for defining a UNIQUE Constraint is as follows:Д¬olumn_name column_DataType UNIQUE,Д®mp_name varchar(25) CONSTRAINT emps_emnm_nn NOT NULL,Д®mp_phone varchar(25)CONSTRAINT emps_empn_uq UNIQUE) In SQL Server, the Unique constraint requires that every value in a column (or set of columns) be unique. This constraint can only be defined at the column level The syntax for defining a Not Null constraint is as follows:Д¬olumn_name column_DataType NOT NULL,Д®mp_name varchar(25) CONSTRAINT emps_emnm_nn NOT NULL) In SQL Server, the Not Null constraint ensures that the column contains no NULL values. Please note вЂ“ the square brackets in this demonstration (and in those that follow) indicate that what enclosed within them is optional, the square brackets are not part of the CREATE TABLE statement. (emp_id decimal(3) CONSTRAINT emps_empid_pk PRIMARY KEY, The syntax for defining a Primary Key Constraint is as follows:Д¬olumn_name column_DataType PRIMARY KEY, Only one Primary Key can be created for each table.

In SQL Server, the Primary Key constraint is a column (or a set of columns) that uniquely identifies each row in the table, this constraint enforces uniqueness and ensures that no column that is part of the Primary Key can hold a NULL value. The following naming convention is commonly used by many database developers : Constraint_name вЂ“ although not mandatory, it is always advisable to give the constraint a name, thereby allowing you to easily identify it.Constraint_type вЂ“ the type of the constraint to be enforced on the column (for example, Unique or Not Null).A constraint at the column level has the following structure:Д¬ONSTRAINT constraint_name constraint_type.Is created as part of the column definition.Constraints can be definedВ at the column or table level. To define a Default value, use this syntax:Д¬onstraints enforce rules on the data in a table whenever a row is inserted, deleted, or updated. The default value can be a literal value, an expression, or a SQL Function, such as GETDATE(). Precision вЂ“ number of digits, Scale вЂ“ how many of the digits are located after the decimal pointДЄ column can be given a default value using the DEFAULT keyword.В The DEFAULT keyword provides a default value to a column when the SQL Server INSERT INTO statement does not provide a specific value. The value within the brackets indicates the maximum size of each field in the column (in characters) SQL Server CREATE TABLE statement is used to create new tables in the database.

The next postВ will describeВ how to use the SQL ServerВ ALTER TABLE statement. This tutorial allows you to become familiar with the following topics:

#Sql server create table how to

In this post you will learn how to create and delete tables.

The DDL statements are a subset of SQL statements used to create, modify, or remove database structures. This tutorial is the first part of two posts describing DDL (Data Definition Language) statements in SQL Server. This SQL tutorialВ explains how to use the CREATE TABLE statement in SQL Server.