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MySQL Datatypes

This appendix explains the different datatypes used in MySQL.

As explained in Chapter 1, “Understanding SQL,” datatypes are basically rules that define what data may be stored in a column and how that data is actually stored.

Datatypes are used for several reasons:

  • Datatypes enable you to restrict the type of data that can be stored in a column. For example, a numeric datatype column accepts only numeric values.

  • Datatypes allow for more efficient storage internally. For example, numbers and datetime values can be stored in a more condensed format than can text strings.

  • Datatypes allow for alternate sorting orders. If everything is treated as strings, 1 comes before 10, which comes before 2. (Strings are sorted in dictionary ...

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