Select Clause
- Last Updated: May 15, 2020
- 2 minute read
- DataDirect Connectors
- JDBC
- IBM Db2 5.1
- MySQL 5.1
- Progress OpenEdge 5.1
- SAP Sybase 5.1
- Documentation
Purpose
Specifies a list of column expressions that identify columns of values that you want to retrieve or an asterisk (*) to retrieve the value of all columns.
Syntax
SELECT [{LIMIT offsetnumber | TOP number}] [ALL | DISTINCT]
{* | column_expression [[AS] column_alias] [,column_expression [[AS] column_alias], ...]}
[INTO [DISK | TEMP] new_table]
where:
- LIMIT offset number
- creates the result set for the Select statement first and then discards the first
number of rows specified by offset and returns the number of
remaining rows specified by number. To not discard any of the rows,
specify
0for offset, for example, LIMIT 0 number. To discard the first offset number of rows and return all the remaining rows, specify0for number, for example, LIMIT offset 0. - TOP number
- is equivalent to
LIMIT 0number. - column_expression
- can be simply a column name (for example,
last_name). More complex expressions may include mathematical operations or string manipulation (for example,salary * 1.05). See SQL Expressions for details. column_expression can also include aggregate functions. See Aggregate Functions for details. - column_alias
- can be used to give the column a descriptive name. For example, to assign the alias department to the column dep:
- DISTINCT
- eliminates duplicate rows from the result of a query. For example:
- INTO
- copies the result set into new_table.
INTO DISKcreates the new table in cached memory.INTO TEMPcreates a temporary table.
Notes
- Separate multiple column expressions with commas (for example,
SELECT last_name, first_name, hire_date). - Column names can be prefixed with the table name or table alias. For example,
SELECT emp.last_name or e.last_name, whereeis the alias for the tableemp. - NULL values are not treated as distinct from each other. The default behavior is that
all result rows be returned, which can be made explicit with the keyword
ALL.