- The “WHERE” clause lets us specify particular criteria for copying the data from the actual table to the newly created table. Different clauses can be used with the “SELECT INTO” statement to perform different operations on the tables, such as the WHERE, INNER JOIN, GROUP BY, etc. ...
In PostgreSQL, theEXISTSoperator/clause checks the existence of a record within the subquery. It receives a subquery as an argument, and depending on the existence of the targeted row or record, it returns true or false. The following aspects of the PostgresEXISTSoperator will be discussed in ...
Writing a CTE in SQL Server is done in a similar way to writing a CTE in Oracle, MySQL, and PostgreSQL. Let’s take a look at some examples. WITH Clause Example We can use the employee database to demonstrate some examples. The SQL to create the sample data is available at the top ...
In the lastINclause, we can specify the schema names of our interest. 2. Getting the size of Database Getting the physical storage size of a database is very helpful in database planning. Use the following command to get the size of a PostgreSQL database in bytes: 1 SELECTpg_database_...
Additionally, PostgreSQL provides the WITH ORDINALITY clause that can be applied to any SRF to generate an additional, incrementing BIGINT column. The best part? It doesn't require a second pass through the data in order to generate this value! SELECT ts AS time, rownum FROM generate_series...
For more information, see Scheduling maintenance with the PostgreSQL pg_cron extension. Run the command UPDATE partman.part_config to adjust the pg_partman settings for the data_mart.events table. Run the command SET . . . to configure the data_mart.events table, with these clauses: ...
The IN Operator is used to replace multiple OR conditions. To understand this let us take an example below. In the first query below, I used the Person table, and in the Where clause filtered for the FirstName column which was used two times combined with the OR condition, at the first...
represents the total length of the string passed to theLENGTH()function. Users can use theLENGTH()function with the collaboration of theWHEREclause to fetch only those strings that meet the length criteria. This blog post demonstrated the working of the LENGTH() function via practical examples....
PostgreSQL DISTINCT Clause examples: generating metrics Let’s generate some metrics! In order to demonstrate this improved performance three tables were created, without indexes, and populated with approximately 5,000,000 records. Notice the number of columns for each table i.e. one, five, and ...
The WHERE clause can be used in JSON operator to filter the returning rows. For example, SELECT info ->> 'customer' AS customer FROM orders WHERE info -> 'items' ->> 'product' = 'Books'; This query can find out which customer bought books from your store. ...