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Logical data types are used to represent the concepts of true, false, or NULL . Typically, this data type is useful as a flag that indicates the current state of a record. The true and false values are self-explanatory, while the value NULL usually indicates the equivalent of "unknown." BOOLEANDescriptionHolds a logical true , a logical false , or a NULL value. InputsTRUE, t, true, y, yes, 1 ”All valid TRUE values. FALSE, f, false, n, no, ”All valid FALSE values. NULL ”Valid NULL value. Storage Size1 byte NotesGenerally , it is best to use the TRUE and FALSE input forms for Boolean data. These formats are SQL compatible and generally are more accepted, although some RDBMSs use 1 and 0 for TRUE and FALSE representations. Some of the input values need to be escaped by enclosing them in single quotes (i.e., 't' ). However, the SQL-compliant TRUE and FALSE forms do not require quotations. |
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