Help Center/ Distributed Database Middleware/ User Guide/ SQL Syntax/ DML/ SELECT
Updated on 2022-09-16 GMT+08:00
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SELECT

SELECT is generally used to query data in one or more tables.

Common Syntax

SELECT
[ALL | DISTINCT | DISTINCTROW ]
select_expr
[, select_expr ...]
[FROM table_references [WHERE where_condition]
[GROUP BY {col_name | expr | position} [ASC | DESC], ...]
[HAVING where_condition] [ORDER BY {col_name | expr | position} [ASC | DESC], ...]
[LIMIT {[offset,] row_count | row_count OFFSET offset}]
Table 1 Supported syntax

Syntax

Description

select_expr

Indicates a column that you want to query.

FROM table_references

Indicates the tables that you want to query.

WHERE

Followed by an expression to filter for rows that meet certain criteria.

GROUP BY

Groups the clauses used in SQL in sequence. GROUP BY indicates relationships between statements and supports column names. For example, the HAVING clause must be after the GROUP BY clause and before the ORDER BY clause.

ORDER BY

Indicates relationships between statements. Sorting by column name or by a specified order such as ASC and DESC is supported.

LIMIT/OFFSET

Restrains the offset and size of output result sets, for example, one or two values can be input after LIMIT.

Syntax Description

  • An empty string cannot be used as an alias.
  • SELECT ... GROUP BY ... WITH ROLLUP is not supported.
  • Neither STRAIGHT_JOIN nor NATURAL JOIN is supported.
  • The SELECT FOR UPDATE statement supports only simple queries and does not support JOIN, GROUP BY, ORDER BY, or LIMIT.
  • Each SELECT statement in UNION does not support multiple columns with the same name, for example,

    SELECT id, id, name FROM t1 UNION SELECT pk, pk, name FROM t2 is not supported because this statement has duplicate column names.

Parent topic: DML