Dyntex.net Support Centre: MySQL Reference Manual p.447

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Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

Chapter 6: MySQL Language Reference 447 BIT_AND(expr) Returns the bitwise AND of all bits in expr. The calculation is performed with 64-bit (BIGINT) precision. MySQL has extended the use of GROUP BY. You can use columns or calculations in the SELECT expressions that don't appear in the GROUP BY part. This stands for any possible value for this group. You can use this to get better performance by avoiding sorting and grouping on unnecessary items. For example, you don't need to group on customer.name in the following query: mysql> SELECT order.custid,customer.name,MAX(payments) -> FROM order,customer -> WHERE order.custid = customer.custid -> GROUP BY order.custid; In ANSI SQL, you would have to add customer.name to the GROUP BY clause. In MySQL, the name is redundant if you don't run in ANSI mode. Don't use this feature if the columns you omit from the GROUP BY part aren't unique in the group! You will get unpredictable results. In some cases, you can use MIN() and MAX() to obtain a specic column value even if it isn't unique. The following gives the value of column from the row containing the smallest value in the sort column: SUBSTR(MIN(CONCAT(RPAD(sort,6,' '),column)),7) See Section 3.5.4 [example-Maximum-column-group-row], page 170. Note that if you are using MySQL Version 3.22 (or earlier) or if you are trying to follow ANSI SQL, you can't use expressions in GROUP BY or ORDER BY clauses. You can work around this limitation by using an alias for the expression: mysql> SELECT id,FLOOR(value/100) AS val FROM tbl_name -> GROUP BY id,val ORDER BY val; In MySQL Version 3.23 you can do: mysql> SELECT id,FLOOR(value/100) FROM tbl_name ORDER BY RAND(); 6.4 Data Manipulation: SELECT, INSERT, UPDATE, DELETE 6.4.1 SELECT Syntax SELECT [STRAIGHT_JOIN] [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] [HIGH_PRIORITY] [DISTINCT | DISTINCTROW | ALL] select_expression,... [INTO {OUTFILE | DUMPFILE} 'file_name' export_options] [FROM table_references [WHERE where_definition] [GROUP BY {unsigned_integer | col_name | formula} [ASC | DESC],

MySQL Reference Manual

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