SELECT [ALL | DISTINCT | DISTINCTROW] [HIGH_PRIORITY] [STRAIGHT_JOIN] [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] select_expr [, select_expr ...] [ FROM table_references [WHERE where_condition] [GROUP BY {col_name | expr | position} [ASC | DESC], ... [WITH ROLLUP]] [HAVING where_condition] [ORDER BY {col_name | expr | position} [ASC | DESC], ...] [LIMIT {[offset,] row_count | row_count OFFSET offset}] procedure|[PROCEDURE procedure_name(argument_list)] [INTO OUTFILE 'file_name' [CHARACTER SET charset_name] [export_options]
INTO DUMPFILE 'file_name' | INTO var_name [, var_name] ] |
[[FOR UPDATE | LOCK IN SHARE MODE] [WAIT n | NOWAIT] ] ]
export_options: [{FIELDS | COLUMNS} [TERMINATED BY 'string'] [[OPTIONALLY] ENCLOSED BY 'char'] [ESCAPED BY 'char'] ] [LINES [STARTING BY 'string'] [TERMINATED BY 'string'] ]
SELECT
is used to retrieve rows selected from one or more tables, and can include UNION statements and subqueries.
FROM
clause indicates the table or tables from which to retrieve rows. Use either a single table name or a JOIN
expression. See JOIN
for details. If no table is involved, FROM DUAL can be specified. The PARTITION clause was introduced in MariaDB 10.0. See Partition Pruning and Selection for details.
db_name
.tabl_name
. Each column can also be specified as tbl_name
.col_name
or even db_name
.tbl_name
.col_name
. This allows to write queries which involve multiple databases. See Identifier Qualifiers for syntax details. WHERE
clause, if given, indicates the condition or conditions that rows must satisfy to be selected. where_condition
is an expression that evaluates to true for each row to be selected. The statement selects all rows if there is no WHERE clause. WHERE
clause, you can use any of the functions and operators that MariaDB supports, except for aggregate (summary) functions. See Functions and Operators and Functions and Modifiers for use with GROUP BY (aggregate). HAVING
clauses to group rows together when they have columns or computed values in common. SELECT can also be used to retrieve rows computed without reference to any table.
A SELECT
statement must contain one or more select expressions, separated by commas. Each select expression can be one of the following:
*
to select all columns from all tables in the FROM
clause. tbl_name.*
to select all columns from just the table tbl_name. When specifying a column, you can either use just the column name or qualify the column name with the name of the table using tbl_name.col_name
. The qualified form is useful if you are joining multiple tables in the FROM
clause. If you do not qualify the column names when selecting from multiple tables, MariaDB will try to find the column in each table. It is an error if that column name exists in multiple tables.
You can quote column names using backticks. If you are qualifying column names with table names, quote each part separately as `tbl_name`.`col_name`
.
If you use any grouping functions in any of the select expressions, all rows in your results will be implicitly grouped, as if you had used GROUP BY NULL
.
DISTINCT
A query may produce some identical rows. By default, all rows are retrieved, even when their values are the same. To explicitly specify that you want to retrieve identical rows, use the ALL
option. If you want duplicates to be removed from the resultset, use the DISTINCT
option. DISTINCTROW
is a synonym for DISTINCT
. See also COUNT DISTINCT and SELECT UNIQUE in Oracle mode.
The INTO
clause is used to specify that the query results should be written to a file or variable.
The reverse of SELECT INTO OUTFILE
is LOAD DATA.
Set the lock wait timeout. See WAIT and NOWAIT.
Passes the whole result set to a C Procedure. See PROCEDURE and PROCEDURE ANALYSE (the only built-in procedure not requiring the server to be recompiled).
max_statement_time
clauseBy using max_statement_time
in conjunction with SET STATEMENT
, it is possible to limit the execution time of individual queries. For example:
SET STATEMENT max_statement_time=100 FOR SELECT field1 FROM table_name ORDER BY field1;
© 2019 MariaDB
Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/select/