Planning Tables
Creating a table involves a series of steps that begins with design and ends with issuing a SQL command. Following is an outline of the process for creating tables without any SQL-92 constraints. It assumes you've already designed and normalized your database and therefore know which columns will be in each table.
1. | Decide on the datatype (and length, precision, and scale, if required) of each column. |
2. | Decide which columns should accept null values and which should not. |
3. | Decide which columns need to be unique, that is, cannot allow duplicate values. (In a system that doesn't use constraints, you'll enforce uniqueness with indexes, discussed in this chapter and in Chapter 10. Information on PRIMARY KEY and UNIQUE constraints ... |
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