Found 32 Questions For SQL

Finding the 2nd Highest Salary of Employees in SQL

Updated on 20-Jun-2024 16:40:55
Finding the 2nd highest salary in an employee database is a common SQL problem that can be approached in multiple ways. This article explores several methods, using various SQL constructs and functions, with detailed examples and explanations. Method 1: Using Subquery with LIMIT and OFFSET One straightforward method is to use a subquery with `LIMIT` and `OFFSET` to fetch the 2nd highest salary. SELECT DISTINCT salary FROM employees ORDER BY salary DESC LIMIT 1 OFFSET 1; Explanation: `SELECT DIS... Read Mores

What is a Nested Field in BigQuery ?

Updated on 10-Jun-2024 16:48:33
Google BigQuery is a highly scalable, serverless data warehouse designed to enable fast SQL queries using the processing power of Google's infrastructure. One of its powerful features is the ability to handle complex data structures, particularly nested fields. Understanding nested fields in BigQuery is crucial for efficiently managing and querying semistructured data. Introduction to Nested Fields in BigQuery In traditional relational databases, data is stored in tables with a flat schema, wher... Read Mores

Create Function to Insert Post and Update Post in Single Function using PHP

Updated on 23-Mar-2023 9:12:24
Hello there, In this tutorial we will learn how to create function to insert post and update post in single function using core php, here's an example function that can both insert a new post and update an existing post in a single function using PHP's core SQL functions: function savePost($postData) { // Connect to the database $conn = mysqli_connect("localhost", "username", "password", "database_name"); // Check if the connection was successful if (!$conn) { die("Connection failed... Read Mores

How to Get the Value from a key pair using PHP

Updated on 02-Apr-2023 13:58:39
Hello there, In this tutorial we will learn how to get the value from a key using PHP SQL key pair, you can use the SELECT statement in SQL and fetch the result in PHP using MySQLi. Here's an example using MySQLi: <?php // Set up database connection $servername = "localhost"; $username = "username"; $password = "password"; $dbname = "database_name"; $conn = mysqli_connect($servername, $username, $password, $dbname); // Check connection if (!$conn) { die("Connection failed: " . mysqli_co... Read Mores

How to Store Array Data To Database to a Single Column Without serialize() & json_encode() Function

Updated on 16-Mar-2024 11:21:06
If you don't want to use serialize() or json_encode() to store the $insData array data to a single column (Key Value Pair) in a MySQL database, you can use a custom delimiter to separate the values and then store the concatenated string in a single column. Here's an example: // Step 1: Connect to the MySQL database $servername = "localhost"; $username = "your-username"; $password = "your-password"; $dbname = "your-database"; $conn = mysqli_connect($servername, $username, $password, $dbname... Read Mores

How To Get the Value from a Database using PHP Key Pair

Updated on 02-Apr-2023 13:58:57
To get the value from a database using PHP key pair, you can use the SELECT statement in SQL and fetch the result in PHP using MySQLi extension. Here's an example using MySQLi: <?php // Set up database connection $servername = "localhost"; $username = "username"; $password = "password"; $dbname = "database_name"; $conn = mysqli_connect($servername, $username, $password, $dbname); // Check connection if (!$conn) { die("Connection failed: " .mysqli_connect_error()); } // Define key ... Read Mores

How to Get All Data of Particular ID and Display using Core PHP 8

Updated on 15-Mar-2023 13:01:58
Hello Friends, In this tutorial we will learn how to retrieve data from a database using PHP 8, you can follow these general steps: Connect to the database using the mysqli_connect() function. Write and execute an SQL query to retrieve the data you need. Fetch the data from the result set and store it in a PHP variable. Close the database connection. Here's an example of how to retrieve data of a particular ID and display it using core PHP version 8: <?php// Step 1: Connect to the data... Read Mores

How to Find the Nth Highest Salary in SQL ?

Updated on 20-Jun-2024 17:29:50
Finding the nth highest salary in SQL is a common interview question and a practical task in database management. Here are several approaches to solve this problem, each with detailed explanations and examples. We'll assume we have a table `Employee` with columns `id`, `name`, and `salary`. ID Name Salary 1 Alice 60000 2 Bob 70000 3 Charlie 80000 4 David 70000 5 Eve 90000 1. Using Subquery with `DISTINCT` and `LIMIT`/`OFFSET` This approach involves using a subquery to first s... Read Mores

How to insert multiple rows in SQL ?

Updated on 16-Dec-2021 16:49:13
To insert multiple rows in SQL we can follow the below syntax: INSERT INTO table_name (column1, column2,column3...) VALUES (value1, value2, value3…..), (value1, value2, value3….), ... (value1, value2, value3); We start off by giving the keywords INSERT INTO then we give the name of the table into which we would want to insert the values. We will follow it up with the list of the columns, for which we would have to add the values. Then we will give in the VALUES key... Read Mores

What is a trigger in SQL ?

Updated on 16-Dec-2021 16:46:22
A trigger is a stored program in a database which automatically gives responses to an event of DML operations done by insert, update, or delete. In other words, is nothing but an auditor of events happening across all database tables. Let’s look at an example of a trigger : CREATE TRIGGER bank_trans_hv_alert BEFORE UPDATE ON bank_account_transaction FOR EACH ROW begin if( abs(:new.transaction_amount)>999999)THEN RAISE_APPLICATION_ERROR(-20000, 'Account transaction exceedi... Read Mores
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