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数据库连接 A string is an expression in which there are all the parameters necessary to establish a connection from a terminal device to a database. It contains databases 用户名 , 密码 , 名称 , 主机地址 and 端口 . This con...

if Statement evaluates a condition by returning true or false value. We can use it to perform condition based queries. This article will teach you how to write if conditional statements and understand how conditional statements can help you...

This article guides you through using the UPDATE and JOIN statements to update a table. Generate a shipment example in PostgreSQL Consider a store that sells food. Every time a shipment arrives, the price of the product is updated to reflec...

This article shows how to check the version of Postgres. Checking Postgres Version in Windows C: \ Users \ Admin psql -- version psql ( PostgreSQL ) 14.0 C : \ Users \ Admin postgres -- version postgres ( PostgreSQL ) 14.0 The version shown...

PostgreSQL is an object-relational database system, which means it can support more complex data types than its competitor MySQL. Apart from the above differences, when writing queries for PostgreSQL and MySQL or other database systems, the...

This article discusses how to import SQL files in PostgreSQL. psql Import SQL files in PostgreSQL using command To import the SQL file, run the following command: psql - U dbuser - h localhost databasename filename. sql If the file is locat...

This article will discuss creating schemas in PostgreSQL using SQL queries or psql. CREATE SCHEMA Use the statement to create a pattern in SQL query To create a new schema, execute the following command. CREATE SCHEMA test_schema To view al...

Today, we will learn how to find a value in a PostgreSQL string and select it if it matches certain conditions. Suppose you have a string carabc and want to see if it contains a value car . Therefore, you will try to use a function that tel...

PostgreSQL , also known as Postgres, is a leading object-relational database system. It is popular because it is highly compliant with the SQL standard and includes additional features that simplify processing complex data sets at scale. Po...

Sometimes, we need to find a specific document using special properties like string length. In this article, we will see how to find a specific document using string length in MongoDB, and we will also see an example on this topic for easy...

When working with projects where you need to validate the size of an array or find elements whose size is greater or less than a certain length, you might use MongoDB operators such as $size, $where, $exists, etc. The methods discussed belo...

In this article, we will address how to use the MongoDB distinct() method to return unique values. In addition, returning unique values ​​in arrays and fields is discussed. In MongoDB, sometimes you may want to present or return unique...

This article will explain how to delete a user from a MongoDB database. In addition, we will see an example to make the topic easier to understand. Deleting a User from a MongoDB Database Sometimes we need to remove a particular user from t...

This article will introduce various methods of sorting timestamps in MongoDB. Sorting by timestamp in MongoDB sort() The method will sort documents in MongoDB. The method accepts a document containing a list of fields and the order in which...

This article will discuss how the $unset operator works in MongoDB. Additionally, we will demonstrate the use of this operator to remove a field from all documents in a MongoDB collection. $unset operator in MongoDB $unset is an operator us...