Restrictions on column values

Some columns of a table might not allow null values. If you attempt to insert NULL in such a column, the statement is rejected. Other columns in the table might not permit duplicate values. If you specify a value that is a duplicate of one that is already in such a column, the statement is rejected. Some columns might even restrict the possible column values allowed. Use data integrity constraints to restrict columns. For more information, see Data integrity.

Restriction: Do not specify the currency symbols for columns that contain money values. Just specify the numeric value of the amount.

The database server can convert between numeric and character data types. You can give a string of numeric characters (for example, '-0075.6') as the value of a numeric column. The database server converts the numeric string to a number. An error occurs only if the string does not represent a number.

You can specify a number or a date as the value for a character column. The database server converts that value to a character string. For example, if you specify TODAY as the value for a character column, a character string that represents the current date is used. (The DBDATE environment variable specifies the format that is used.)