Category: 3. Postgres SQL

The PostgreSQL DISTINCT keyword is used in conjunction with SELECT statement to eliminate all the duplicate records and fetching only unique records. There may be a situation when you have multiple duplicate records in a table. While fetching such records, it makes more sense to fetch only unique records instead of fetching duplicate records. Syntax Example First,…

The HAVING clause allows us to pick out particular rows where the function’s result meets some condition. The WHERE clause places conditions on the selected columns, whereas the HAVING clause places conditions on groups created by the GROUP BY clause. Syntax The following is the position of the HAVING clause in a SELECT query −…

In PostgreSQL, the WITH query provides a way to write auxiliary statements for use in a larger query. It helps in breaking down complicated and large queries into simpler forms, which are easily readable. These statements often referred to as Common Table Expressions or CTEs, can be thought of as defining temporary tables that exist…

The PostgreSQL GROUP BY clause is used in collaboration with the SELECT statement to group together those rows in a table that have identical data. This is done to eliminate redundancy in the output and/or compute aggregates that apply to these groups. The GROUP BY clause follows the WHERE clause in a SELECT statement and precedes the…

The PostgreSQL ORDER BY clause is used to sort the data in ascending or descending order, based on one or more columns. Syntax The basic syntax of ORDER BY clause is as follows −SELECT column-list FROM table_name [WHERE condition] [ORDER BY column1, column2, .. columnN] [ASC | DESC]; You can use more than one column in the…

The PostgreSQL LIMIT clause is used to limit the data amount returned by the SELECT statement. Syntax The basic syntax of SELECT statement with LIMIT clause is as follows − The following is the syntax of LIMIT clause when it is used along with OFFSET clause − LIMIT and OFFSET allow you to retrieve just a portion…

The PostgreSQL LIKE operator is used to match text values against a pattern using wildcards. If the search expression can be matched to the pattern expression, the LIKE operator will return true, which is 1. There are two wildcards used in conjunction with the LIKE operator − The percent sign represents zero, one, or multiple numbers or characters.…

The PostgreSQL DELETE Query is used to delete the existing records from a table. You can use WHERE clause with DELETE query to delete the selected rows. Otherwise, all the records would be deleted. Syntax You can combine N number of conditions using AND or OR operators. Example The following is an example, which would DELETE a…

The PostgreSQL UPDATE Query is used to modify the existing records in a table. You can use WHERE clause with UPDATE query to update the selected rows. Otherwise, all the rows would be updated. Syntax You can combine N number of conditions using AND or OR operators. Example The following is an example, which would update ADDRESS…

PostgreSQL SELECT statement is used to fetch the data from a database table, which returns data in the form of result table. These result tables are called result-sets. Syntax Here, column1, column2…are the fields of a table, whose values you want to fetch. If you want to fetch all the fields available in the field then you…