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This article introduces the relevant knowledge of "what are PostgreSQL expressions?". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

An expression is a combination of one or more values, operators, and PostgreSQL functions that evaluate the resulting values.

The expression of PostgreSQL is similar to the formula and is written in the query language. You can also use specific datasets to query the database.

Syntax:

The basic syntax for considering the SELECT statement is as follows:

SELECT column1, column2, columnN FROM table_name WHERE [CONTION | EXPRESSION]

PostgreSQL expressions, which are different types mentioned below:

PostgreSQL Boolean expression:

PostgreSQL's Boolean expression matches a single value based on the fetched data. The following is the syntax:

SELECT column1, column2, columnN FROM table_name WHERE SINGLE VALUE MATCHTING EXPRESSION

Consider that table COMPANY has the following record:

Testdb# select * from COMPANY Id | name | age | address | salary-- +-1 | Paul | 32 | California | 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall | 45000 7 | | James | 24 | Houston | 10000 (7 rows) |

Here is a simple example of a Boolean expression that uses PostgreSQL:

Testdb=# SELECT * FROM COMPANY WHERE SALARY = 10000

The above PostgreSQL statement produces the following results:

Id | name | age | address | salary-- +-7 | James | 24 | Houston | 10000 1 row)

PostgreSQL-numeric expression:

These expressions are used to perform any query that performs any mathematical operation. The following is the syntax:

SELECT numerical_expression as OPERATION_NAME [FROM table_name WHERE CONDITION]

Here numeric expressions are used for mathematical expressions or any formula. Here is a simple example of using SQL numeric expressions:

Testdb=# SELECT (15 + 6) AS ADDITION

The above PostgreSQL expression produces the following results:

Addition-21 (1 row)

There are several built-in functions like avg (), sum (), count () etc to perform what is known as aggregate data calculations against a table or a specific table column.

Testdb=# SELECT COUNT (*) AS "RECORDS" FROM COMPANY

The above PostgreSQL table produces the following results:

RECORDS-7 (1 row)

PostgreSQL date expression:

Date expressions return the current system date and time values, and these expressions will be used for various data operations.

Testdb=# SELECT CURRENT_TIMESTAMP

The above PostgreSQL table produces the following results:

Now-2013-05-06 1438 PostgreSQL VLV 28.078 05RV 30 1 row) "what are the PostgreSQL expressions?" Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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