"INSERT INTO" Statements with INDENTITY Columns

JDBC for SQL Server - Herong's Tutorial Examples

∟"INSERT INTO" Statements with INDENTITY Columns

This section describes what will happen if you try to insert rows with values for INDENTITY columns.

An INDENTITY column is a special column in a table that defined to have it value automatically added with a sequence number generator. An INDENTITY column is normally used for the primary key column in a table.

For example, we can add a new column, CustomID, into my Customer table and make it as an INDENTITY column.

herong> sqlcmd -S localhost\SQLEXPRESS -E

1> use AdventureWorks2014
2> go
1> alter table Herong.Customer add CustomerID int IDENTITY
2> go

If you try to add values to an INDENTITY column in INSERT statements, you will get an error as shown in the sample program below:

/* InsertIdentity.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
public class InsertIdentity {
  public static void main(String [] args) {
    Connection con = null;
    try {

      con = DriverManager.getConnection(
          "jdbc:sqlserver://localhost\\SQLEXPRESS;"
        + "user=herong;password=T0pSecret;"
        + "database=AdventureWorks2019");
      Statement sta = con.createStatement();

// insert a single row
      int count = sta.executeUpdate(
        "INSERT INTO Herong.Customer"
        + " (CustomerID, FirstName, LastName, ModifiedDate)"
        + " VALUES (1001, 'Herong', 'Yang', '2007-04-01')");
      System.out.println("Number of rows inserted: "+count);

      sta.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

Here is the error message from this program:

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar InsertIdentity

com.microsoft.sqlserver.jdbc.SQLServerException:
Cannot insert explicit value for identity column
in table 'Customer' when IDENTITY_INSERT is set to OFF.