For example, the following statement changes the data type of a field in the Employees table called ZipCode (originally defined as Integer) to a 10-character Text field:ĪLTER TABLE Employees ALTER COLUMN ZipCode TEXT(10) You specify the field name, the new data type, and an optional size for Text and Binary fields. Use ALTER COLUMN to change the data type of an existing field. If you specify NOT NULL for a field then new records are required to have valid data in that field. You can also define an index on that field. For example, the following statement adds a 25-character Text field called Notes to the Employees table:ĪLTER TABLE Employees ADD COLUMN Notes TEXT(25) You specify the field name, data type, and (for Text and Binary fields) an optional size. Use ADD COLUMN to add a new field to the table. Using the ALTER TABLE statement you can alter an existing table in several ways. The name of the multiple-field index to be removed. The definition of a multiple-field index to be added to table. The field size in characters (Text and Binary fields only). Or, the name of the field to be altered in table. The name of the field to be added to or deleted from table. The ALTER TABLE statement has these parts: Note: The Microsoft Access database engine does not support the use of ALTER TABLE, or any of the data definition language statements, with non-Microsoft Access databases.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |