My. SQL My. SQL 5. Reference Manual 1. SELECT Syntax. A selectexpr can be given an alias. AS. aliasname. The alias is. GROUP BY, ORDER BY, or. HAVING clauses. For example. SELECT CONCATlastname, ,firstname AS fullname. FROM mytable ORDER BY fullname. The AS keyword is optional when aliasing a. Db2 Sql Select For Update Example' title='Db2 Sql Select For Update Example' />Craig S. Mullins Database Performance Management Return to Home Page. October 2004 Using Dynamic SQL for Maximum Flexibility. B12037_01/appdev.101/a42525/image044.gif' alt='Db2 Sql Select For Update Example' title='Db2 Sql Select For Update Example' />The. SELECT CONCATlastname, ,firstname fullname. FROM mytable ORDER BY fullname. However, because the AS is optional, a. My. SQL. interprets the second as an alias name. For example, in the. SELECT columna columnb FROM mytable. COBOL, DB2, SQL, Select Into, Embedded SQL, Model Program. SELECT can also be used to retrieve rows computed without reference to any table. For example mysql SELECT 1 1 2. For this reason, it is good practice to be in the habit of. AS explicitly when specifying column. It is not permissible to refer to a column alias in a. WHERE clause, because the column value. WHERE. clause is executed. See Section B. 5. Problems with Column Aliases. The FROM. tablereferences clause. If. you name more than one table, you are performing a join. For. information on join syntax, see Section 1. JOIN Syntax. For. AS alias indexhint. The use of index hints provides the optimizer with information. For a. description of the syntax for specifying these hints, see. Db2 Sql Select For Update Example' title='Db2 Sql Select For Update Example' />Section 8. Index Hints. You can use SET. My. SQL to prefer key scans. See. Section 5. 1. Server System Variables. You can refer to a table within the default database as. You can refer to a column as. You need not specify a tblname or. See Section 9. 2. Identifier Qualifiers, for. A table reference can be aliased using. AS. aliasname or. SELECT t. 1. name, t. FROM employee AS t. AS t. 2. WHERE t. SELECT t. 1. name, t. FROM employee t. 1, info t. WHERE t. 1. name t. Columns selected for output can be referred to in. ORDER BY and GROUP BY. Column positions are integers and begin with 1. SELECT college, region, seed FROM tournament. ORDER BY region, seed. SELECT college, region AS r, seed AS s FROM tournament. ORDER BY r, s. SELECT college, region, seed FROM tournament. ORDER BY 2, 3. To sort in reverse order, add the DESC. ORDER BY clause that you are sorting by. The default is ascending order this can be specified. ASC keyword. If ORDER BY occurs within a subquery and. ORDER BY takes precedence. For example. results for the following statement are sorted in descending. SELECT. ORDER BY a ORDER BY a DESC. Use of column positions is deprecated because the syntax has. SQL standard. If you use GROUP BY, output rows are sorted. GROUP BY columns as if you. ORDER BY for the same columns. To. avoid the overhead of sorting that GROUP BY. ORDER BY NULL. SELECT a, COUNTb FROM testtable GROUP BY a ORDER BY NULL. Relying on implicit GROUP BY sorting that. ASC or. DESC designators is deprecated. To produce. a given sort order, use explicit ASC or. DESC designators for GROUP. BY columns or provide an ORDER BY. When you use ORDER BY or GROUP. BY to sort a column in a. SELECT, the server sorts values. My. SQL extends the GROUP BY clause so that. ASC and. DESC after columns named in the clause. SELECT a, COUNTb FROM testtable GROUP BY a DESC. My. SQL extends the use of GROUP BY to permit. GROUP. BY clause. If you are not getting the results that. GROUP BY found in. Section 1. 2. 1. 6, Aggregate GROUP BY Functions. GROUP BY permits a WITH. ROLLUP modifier. See. Section 1. 2. 1. 6. GROUP BY Modifiers. The HAVING clause is applied nearly last. LIMIT is applied after. HAVING. The SQL standard requires that HAVING must. GROUP BY. clause or columns used in aggregate functions. However, My. SQL. HAVING to refer to columns in the. SELECT list and columns in. If the HAVING clause refers to a column. In the following. SELECT COUNTcol. AS col. FROM t GROUP BY col. HAVING col. 2 2. Preference is given to standard SQL behavior, so if a. HAVING column name is used both in. GROUP BY and as an aliased column in the. GROUP BY column. Do not use HAVING for items that should be. WHERE clause. For example, do not. SELECT colname FROM tblname HAVING colname 0. Write this instead. SELECT colname FROM tblname WHERE colname 0. The HAVING clause can refer to aggregate. WHERE clause cannot. SELECT user, MAXsalary FROM users. GROUP BY user HAVING MAXsalary 1. This did not work in some older versions of My. SQL. My. SQL permits duplicate column names. That is, there can be. This is an extension to standard SQL. Because My. SQL. also permits GROUP BY and. HAVING to refer to. SELECT 1. 2 AS a, a FROM t GROUP BY a. In that statement, both columns have the name. To ensure that the correct column is. My. SQL resolves unqualified column or alias references in. ORDER BY clauses by searching in the. FROM clause. For GROUP BY or HAVING. FROM clause before. For GROUP BY and. HAVING, this differs from the pre My. SQL 5. 0. behavior that used the same rules as for ORDER. The LIMIT clause can be used to constrain. SELECT statement. LIMIT takes one or two numeric arguments. Within prepared statements, LIMIT. Within stored programs, LIMIT. My. SQL 5. 5. 6. With two arguments, the first argument specifies the offset of. The offset of the initial row is 0. SELECT FROM tbl LIMIT 5,1. Retrieve rows 6 1. To retrieve all rows from a certain offset up to the end of. This statement retrieves all rows from the 9. SELECT FROM tbl LIMIT 9. A Simplified Trusted Software Stack Definition here. With one argument, the value specifies the number of rows to. SELECT FROM tbl LIMIT 5 Retrieve first 5 rows. In other words, LIMIT. LIMIT 0. rowcount. For prepared statements, you can use placeholders. The. following statements will return one row from the. SET a1. PREPARE STMT FROM SELECT FROM tbl LIMIT. EXECUTE STMT USING a. The following statements will return the second to sixth row. SET skip1 SET numrows5. PREPARE STMT FROM SELECT FROM tbl LIMIT ,. EXECUTE STMT USING skip, numrows. For compatibility with Postgre. SQL, My. SQL also supports the. LIMIT rowcount OFFSET. If LIMIT occurs within a subquery and also. LIMIT takes precedence. For example, the. SELECT. LIMIT 1 LIMIT 2. A PROCEDURE clause names a procedure that. For an example, see. Section 8. 4. 2. 4, Using PROCEDURE ANALYSE, which describes. ANALYSE, a procedure that can be used to. A PROCEDURE clause is not permitted in a. UNION statement. The SELECT. INTO form of SELECT. For more information, see. Section 1. 3. 2. 9. SELECT. INTO Syntax. If you use FOR UPDATE with a storage engine. Using. LOCK IN SHARE MODE sets a shared lock that. See. Section 1. 4.