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Oracle SQL: SELECT

The select statement is used to get data stored in tables.

Oracle 23c: No table (dual) required anymore

Prior to Oracle 23c, the select statement required at least one table to select from. In order to evaluate an expression, this table typically was dual:

select
   sysdate as this_moment,
   7*6     as result
from
   dual;

With 23c, dual is not needed anymore:

select
   sysdate as this_moment,
   7*6     as result;

See also

SQL clauses related to the select statement include:

but see also the pivot and the model clause.

analytic functions

hierarchical queries

TOP N queries: selecting first n rows / paging.

create table … as select …

insert into … select …

Select a sample of records from a table.

Selecting from SQL macro tables

select ai

The column pq_status in v$session shows if parallel query mode is enabled in a particular session.

The result of a select statement might be (dynamically) stored in a materialized view.

The OraOLEDB specific connection string attribute MetaDataCacheSize

The pseudo column rownum assigns a row number to each record returned by a select statement.

SELECT DISTINCT

The SELECT STATEMENT plan operation.

The SQL*Plus COPY command copies the result of a select statement to another database.

The SQL*Plus value of arraysize specifies the number or records that SQL*Plus fetches from the database.

The value of rowlimit specifies the maximum number or records that are displayed (not that are fetched).

Virtual Private Database

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/developm...', 1740442469, '18.217.47.171', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/development/databases/Oracle/SQL/select/index(117): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78