(mysql.info) null-values

Info Catalog

(mysql.info) bit-field-values

(mysql.info) literals

 
 9.1.6 `NULL' Values
 -------------------
 
 The `NULL' value means `no data.' `NULL' can be written in any
 lettercase.
 
 Be aware that the `NULL' value is different from values such as `0' for
 numeric types or the empty string for string types. See 
 problems-with-null.
 
 For text file import or export operations performed with `LOAD DATA
 INFILE' or `SELECT ... INTO OUTFILE', `NULL' is represented by the `\N'
 sequence. See  load-data.
 

Info Catalog

(mysql.info) bit-field-values

(mysql.info) literals