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Db2 Insert Statement

6 min read Oct 13, 2024
Db2 Insert Statement

Understanding the DB2 INSERT Statement

The INSERT statement in DB2 is a fundamental command used to add new rows of data into your existing tables. This powerful tool allows you to populate your database with the information needed for your applications.

The Basics of DB2 INSERT Statements

At its core, the INSERT statement in DB2 follows a simple syntax:

INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);

Here's a breakdown of the key components:

  • INSERT INTO: This signifies the intent to insert new data into a table.
  • table_name: The name of the table you want to insert data into.
  • (column1, column2, ...): An optional list of columns you wish to populate. If you omit this list, you must provide values for all columns in the table.
  • VALUES (value1, value2, ...): The values you want to insert into the respective columns. These values must correspond in order and data type to the columns specified in the column list (or to all columns in the table if the column list is omitted).

Let's see an example:

Assume you have a table named employees with columns for employee_id, first_name, last_name, and department. You want to add a new employee record:

INSERT INTO employees (employee_id, first_name, last_name, department) 
VALUES (101, 'John', 'Doe', 'Sales');

This statement will add a new row to the employees table, assigning the provided values to the respective columns.

Key Points to Remember

  • Data Types: The values you provide in the VALUES clause must match the data types of the corresponding columns in the table. For example, you can't insert a string into a numeric column.
  • Column Order: When you specify a column list, the values in the VALUES clause must be in the same order.
  • Missing Columns: If you omit the column list, you need to provide values for all columns in the table, even if they are not explicitly specified.

Adding Data to Specific Columns

What if you only want to insert data into certain columns? You can achieve this by specifying the relevant column names in the column list:

INSERT INTO employees (first_name, last_name) 
VALUES ('Jane', 'Smith');

This statement will insert data into the first_name and last_name columns while leaving the other columns blank.

Specifying Default Values

When you're inserting a new row, the columns not explicitly assigned values in the VALUES clause will be assigned their default values, if any. This is where using DEFAULT comes into play:

INSERT INTO employees (employee_id, first_name, last_name) 
VALUES (102, 'Peter', 'Pan');

In this case, the department column (not specified in the column list) will be filled with its default value, if one exists.

Working with Multiple Rows

You can also insert multiple rows of data at once using the VALUES clause multiple times within the same INSERT statement:

INSERT INTO employees (employee_id, first_name, last_name, department) VALUES 
(103, 'Alice', 'Wonderland', 'Marketing'),
(104, 'Bob', 'Builder', 'Construction');

This statement adds two new rows to the employees table in a single operation.

Handling NULL Values

To explicitly insert a NULL value into a column, use the keyword NULL within the VALUES clause:

INSERT INTO employees (employee_id, first_name, last_name, department) 
VALUES (105, 'Charlie', NULL, 'IT');

This statement inserts NULL into the last_name column.

Conclusion

The INSERT statement is a core functionality in DB2 that allows you to add new rows of data to your tables. Understanding the syntax and its variations is essential for effectively managing your database and populating it with the information needed to support your applications. By mastering the INSERT statement, you gain a powerful tool for building and maintaining your database systems.

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