Duplicate Key Error on Primary Key Columns in SQL Server

Q

What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server?

✍: FYIcenter.com

A

If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow duplicate values. The following tutorial exercise gives you a good example:

SELECT * FROM fyi_links
INSERT INTO fyi_links VALUES (101, 
  'sql.fyicenter.com', 
  NULL,
  0,
  '2006-04-30')
GO
Msg 2627, Level 14, State 1, Line 1
Violation of PRIMARY KEY constraint 
   'PK__fyi_links__03317E3D'. Cannot insert duplicate 
   key in object 'dbo.fyi_links'.
The statement has been terminated.

You are getting this error, because value "101" has already been used by an existing row.

⇒ Inserting Multiple Rows with One INSERT Statement in SQL Server

⇐ Providing Column Names in INSERT Statements in SQL Server

⇑ Using INSERT, UPDATE and DELETE Statements in SQL Server

⇑⇑ SQL Server Database Tutorials

2016-11-02, 1535🔥, 0💬

DML (Data Manipulation Language_Statements in SQL Server
What Are DML (Data Manipulation Language) Statements in SQL Server? DML (Data Manipulation Language) statements are statements to change data values in database tables. The are 3 primary DML statements: INSERT - Inserting new rows into database tables. For example "INSERT INTO fyi_links VALUES (101,... 2016-11-03, 2031🔥, 0💬

Testing Table for DML Statements in SQL Server
How To Create a Testing Table with Test Data in SQL Server? If you want to practice DML statements, like INSERT, UPDATE and DELETE statements, you should create a testing table. The tutorial exercise shows you a good example: CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url VARCHAR(80) NOT NULL, ... 2016-11-03, 1710🔥, 0💬

Using Old Values to Define New Values in UPDATE Statements in SQL Server
How to use old values to define new values in UPDATE statements in SQL Server? If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by column names in the expressions. ... 2016-11-02, 1667🔥, 0💬

DEFAULT - Using Column Default Values in INSERT Statements in SQL Server
How To Use Column Default Values in INSERT Statements in SQL Server? If a column is defined with a default value in a table, you can use the key word DEFAULT in the INSERT statement to take the default value for that column. The following tutorial exercise gives a good example: INSERT INTO fyi_links... 2016-11-03, 1564🔥, 0💬

"INSERT INTO" - Inserting a New Row into a Table in SQL Server
How To Insert a New Row into a Table with "INSERT INTO" Statements in SQL Server? To insert a new row into a table, you can use the INSERT INTO statement with values specified for all columns as in the following syntax: INSERT INTO table_name VALUES (list_of_values_of_all columns) Note that the list... 2016-11-03, 1563🔥, 0💬

Inserting Multiple Rows with One INSERT Statement in SQL Server
How To Insert Multiple Rows with One INSERT Statement in SQL Server? If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. The following tutorial exercise gives you a... 2016-11-02, 1549🔥, 0💬

Duplicate Key Error on Primary Key Columns in SQL Server
What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server? If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow dupl... 2016-11-02, 1536🔥, 0💬

Importance of Column Order in the SET Clause in Update Statements in SQL Server
Is the Order of Columns in the SET Clause Important in SQL Server? The answer is NO. The order of columns in the SET clause of the UPDATE statement is NOT important. You probably already noticed from the previous tutorial. There is a BIG DIFFERENCE among SQL Server, MySQL and Oracle on update multip... 2016-11-02, 1519🔥, 0💬

Updating Values with UPDATE Statements in SQL Server
How To Update Values in a Table with UPDATE Statements in SQL Server? If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: SELECT * FROM fyi_links WHERE id = 101 GO id url notes counts created 101 ... 2016-11-02, 1486🔥, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.