Adding columns when altering a table

Use the Add Column window to add columns to your table. You can add multiple columns before closing this window.

Fields and controls

Authorities and privileges

To add new columns:

1. In the Column name field, type a name for the column that you're adding.
2. Use the Data type box to specify the data type of the column that you're adding.
3. If you specified a data type of CHARACTER, VARCHAR, BLOB, CLOB, DBCLOB, GRAPHIC, or VARGRAPHIC, type the length (byte count) of the column that you're adding in the Length field.
4. If you specified a data type of BLOB, CLOB, or DBCLOB, use the LOB unit box to specify a multiplier for the length of columns.
5. If you specified a data type of DECIMAL:
   1. In the Precision field, type the precision (total number of digits) for the column.
   2. In the Scale field, type the scale (number of digits to the right of the decimal) for the column.
6. If you specified a data type of BLOB, CLOB, DBCLOB, or a distinct type with any of these as source types, specify the LOB options by selecting or clearing the appropriate LOB option check boxes.
7. Optional: If you specified a data type of CHARACTER, VARCHAR, or LONG VARCHAR, select the Bit data check box to specify that the contents of the column be treated as bit (binary) data.
8. If you want to allow the column to contain null values, select the Nullable check box.
9. Optional: If you want the column to contain a default value, select the check box beside the Default field, and type the default value for the column.

   Note:

   You cannot specify a default value if you want the column to be a generated column.

10. Optional: In the Comment field, document the column that you're adding.
11. If you want DB2 to automatically generate values for the column, select Generate column contents.
    • If you want the column to be an identity column, select Identity.

      Note:

      An identity column must have a numeric data type.

      You can specify the following parameters:
      • Initial value to specify the value that will be generated for the first row of the table.
      • Increment to specify the incremental value for each row.
      • Cache value to specify how many identity row values DB2 will maintain in the cache.
      • By default to specify whether DB2 will generate a value for each row that you import or load into the table, even if the input data contains an identity value for the row.
    • If you want to specify the formula by which DB2 generates values, select Formula, and specify the formula.
12. Click on Apply to add the new column.

    You can add up to 500 columns to your table.

13. Click on Cancel to close the Add Column window.
14. If you do not want to make any additional changes to the table, click on OK to alter your table and close the Alter Table notebook. Otherwise, continue on to one or more of the optional tasks.

Related information

• Alter Table -- Overview
• Data types -- See the SQL Reference
• LOB units -- See the SQL Reference
• Default values -- See the SQL Reference
• Null values -- See the SQL Reference
• Adding column-level check constraints
• Selecting predefined columns when altering a table