---
title: "Introduction to SQL"  
description: "SQL stands for Structured Query Language. The structured query language is used to manipulate and access the databases. SQL is an ANSI (American Natio"  
author: "Samuel Fernandes"  
published: 2016-06-30  
updated: 2018-03-16  
canonical: https://www.mindstick.com/blog/11168/introduction-to-sql  
category: "mysql"  
tags: ["database", "sql"]  
reading_time: 11 minutes  

---

# Introduction to SQL

SQL stands for Structured [Query Language](https://www.mindstick.com/forum/158386/what-is-the-purpose-of-the-sqlite-query-language-and-how-does-it-differ-from-other-sql-dialects). The structured query language is used to manipulate and access the databases. SQL is an **ANSI (American National Standard Institute)** standard. Use of SQL:\

· SQL is used to create database.

· SQL is used to create table.

· SQL is used to [insert value in table](https://www.mindstick.com/forum/501/error-while-insert-value-in-table).

· SQL is used to modify value in table.

· SQL is used to delete value in table.

· SQL is used to drop the table.

· SQL is used to drop database.

In this section we will discuss some queries used in databases.

NOTE: SQL is case insensitive means select is same as SELECT.

**Create database**

To create database **CREATE DATABASE** statement is used. Below is the syntax for creating database:

##### Syntax:

CREATE DATABASE name_of_database;

**Example****:**

CREATE DATABASE student;\

student database will be created.

**Create Table**

To create table CREATE [TABLE statement](https://www.mindstick.com/forum/159777/how-to-add-a-new-column-to-an-existing-sql-table-using-the-alter-table-statement) is used. Below is the syntax for creating table:

##### Syntax

```
CREATE TABLE name_of_table(column_name1 data_type(size),column_name2 data_type(size),column_name3 data_type(size),....);
```

## Example:

```
 
CREATE TABLE student
( studentID int,
First Name varchar(55),
Last Name varchar(55),
Address varchar(55),
City varchar(55)
);
```

Student_info table will be created.

**INSERT INTO**

To insert values in the table INSERT INTO statement is used. This statement is used in two ways:

**Syntax:**

1) INSERT INTO name_of_table VALUES (value1, value2, value3,...);\

2) INSERT INTO name_of_table (column1, column2, column3,...)

VALUES (value1, value2, value3,...);

**Example:**

1) INSERT INTO student_info VALUES (1234,'John’,’Smith’,52,’London’); 2) INSERT INTO student_info (studentid, Firstname, Lastname, City)VALUES (1234,'John’,’Smith’,’London’);

**UPDATE**

To update record **UPDATE** statement is used. Below is the syntax for updating record:

**Syntax:**

```
UPDATE name_of_table
SET column1=value1,column2=value2,...
WHERE column=value;
```

**NOTE:** **WHERE clause is used to specify which record is to be updated.**

**Example:**

```
UPDATE student_info
SET FirstName='Jennifer’ WHERE FirstName='John’;
```

**DELETE**

To delete record DELETE statement is used. Below is the syntax for deleting record:

**Syntax:**

```
DELETE FROM name_of_table
WHERE column=value;
```

NOTE: WHERE clause is used to specify which record is to be deleted.

**Example:**

```
DELETE FROM student_info
WHERE firstName='Jennifer' ;
```

Output: Jennifer record will be deleted.

**SELECT**

To select [data from database](https://www.mindstick.com/forum/34370/how-to-populate-google-charts-using-data-from-database-created-via-data-first-asp-dot-net-mvc) [SELECT statement](https://www.mindstick.com/forum/160076/explain-the-sql-select-statement-and-how-it-s-used-to-search-for-data-in-a-database) is used. The result which we get will be stored in result set. Following is the syntax of SELECT statement:

**Syntax:**

```
SELECT column_name1, column_name2
FROM name_of_table;
```

Above syntax is given where particular data is to be selected.

```
SELECT * FROM name_of_table;
```

Above syntax is used to fetch whole record in database.

**Example:**

| \| ## StudentId \| ## Name \| ## Address \| ## Contact Marks \| \| --- \| --- \| --- \| --- \| \| 12ST09 \| John \| USA \| 456788 54 \| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| 12ST11 \| Mickel \| London \| 56276 45 \| \| 12ST12 \| Tom \| New york \| 2898938 43 \| \| 12ST13 \| Hugh \| Luanda \| 2974789 34 \| \| 12ST14 \| John \| Paris \| 232688 56 \| \| 12ST15 \| Jennifer \| USA \| 43762762 67 \| |  |  |  |
| --- | --- | --- | --- |
| ## StudentId | ## Name | ## Address | ## Contact Marks |
| 12ST09 | John | USA | 456788 54 |
| 12ST10 | Royce | Argentina | 457912 34 |
| 12ST11 | Mickel | London | 56276 45 |
| 12ST12 | Tom | New york | 2898938 43 |
| 12ST13 | Hugh | Luanda | 2974789 34 |
| 12ST14 | John | Paris | 232688 56 |
| 12ST15 | Jennifer | USA | 43762762 67 |

SELECT Name, address from student_info;\

**Output:**

| \| ## Name \| ## Address \| \| --- \| --- \| \| John \| USA \| \| Royce \| Argentina \| \| Mickel \| London \| \| Tom \| New york \| \| Hugh \| Luanda \| \| John \| Paris \| \| Jennifer \| USA \| |  |
| --- | --- |
| ## Name | ## Address |
| John | USA |
| Royce | Argentina |
| Mickel | London |
| Tom | New york |
| Hugh | Luanda |
| John | Paris |
| Jennifer | USA |

```
SELECT * FROM student_info;
```

**Output:**

| \| ## StudentId \| ## Name \| ## Address \| ## Contact Marks \| \| --- \| --- \| --- \| --- \| \| 12ST09 \| John \| USA \| 456788 54 \| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| 12ST11 \| Mickel \| London \| 56276 45 \| \| 12ST12 \| Tom \| New york \| 2898938 43 \| \| 12ST13 \| Hugh \| Luanda \| 2974789 34 \| \| 12ST14 \| John \| Paris \| 232688 56 \| \| 12ST15 \| Jennifer \| USA \| 43762762 67 \| |  |  |  |
| --- | --- | --- | --- |
| ## StudentId | ## Name | ## Address | ## Contact Marks |
| 12ST09 | John | USA | 456788 54 |
| 12ST10 | Royce | Argentina | 457912 34 |
| 12ST11 | Mickel | London | 56276 45 |
| 12ST12 | Tom | New york | 2898938 43 |
| 12ST13 | Hugh | Luanda | 2974789 34 |
| 12ST14 | John | Paris | 232688 56 |
| 12ST15 | Jennifer | USA | 43762762 67 |

**DISTINCT**

In a table, a field may have [duplicate values](https://www.mindstick.com/forum/157764/how-to-find-duplicate-values-in-a-sql-table); and you only want distinct values. So, **DISTINCT** keyword is used which will return only different (distinct) values. Following is the syntax of DISTINCT statement:

**Syntax:**

```
SELECT DISTINCT column_name1, column_name2
FROM name_of_table;
```

**Example:**

```
SELECT DISTINCT address  FROM student_info;
```

**output**

| \| USA \| \| --- \| \| Argentina \| \| London \| \| New york \| \| Luanda \| \| Paris \| |
| --- |
| USA |
| Argentina |
| London |
| New york |
| Luanda |
| Paris |

**WHERE**

WHERE clause filter only those data that fulfill a specified criterion. Following is the syntax of DISTINCT statement:

**Syntax:**

```
SELECT column_name1,column_name2
FROM name_of_table
WHERE column_name operator value;
```

**Example:**

```
SELECT * FROM student_info
WHERE address= ‘USA’;
```

## Output:

| \| 12ST09 \| John \| USA \| 456788 54 \| \| \| \| \| --- \| --- \| --- \| --- \| --- \| --- \| --- \| \| 12ST15 \| Jennifer USA \| 43762762 \| 67 \| \| \| \| \| \| \| \| \| \| \| \| |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| 12ST09 | John | USA | 456788 54 |  |  |  |
| 12ST15 | Jennifer USA | 43762762 | 67 |  |  |  |
|  |  |  |  |  |  |  |

**AND & OR**

Like WHERE clause **AND & OR** operator is also used for filter.

The **AND** operator is used when first condition and second condition both are true.

The OR operator is used when either the first condition or second condition is true.

**Example:**

```
SELECT * FROM student_info
WHERE address='Paris'
AND marks='56';
```

## Output:

| \| 12ST14 \| John \| Paris \| 232688 56 \| \| --- \| --- \| --- \| --- \| |  |  |  |
| --- | --- | --- | --- |
| 12ST14 | John | Paris | 232688 56 |

**Example:**

```
SELECT * FROM student_info
WHERE name='John'
OR address='Argentina';
```

**Output:**

| \| 12ST09 \| John \| USA \| 456788 54 \| \| \| \| \| --- \| --- \| --- \| --- \| --- \| --- \| --- \| \| 12ST14 \| John \| Paris \| 232688 \| \| \| \| \| \| \| \| \| \| \| \| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| \| \| \| \| \| \| \| \| \| \| |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| 12ST09 | John | USA | 456788 54 |  |  |  |
| 12ST14 | John | Paris | 232688 |  |  |  |
|  |  |  |  |  |  |  |
| 12ST10 | Royce | Argentina | 457912 34 |  |  |  |
|  |  |  |  |  |  |  |

**ORDER BY**

**ORDER BY**is used to sort the column. By default the records is sorted in [ascending order](https://www.mindstick.com/forum/157178/how-to-filter-1000-of-student-name-in-php-in-ascending-order). For [descending order](https://www.mindstick.com/forum/160082/how-to-sort-the-results-of-an-sql-search-query-in-ascending-and-descending-order) you can use DESC keyword.

**Syntax:**

```
SELECT column_name1, column_name
FROM name_of_table
ORDER BY column_name ;
```

**Example**

```
SELECT * FROM student_info
ORDER BY name;
```

**Output:**

| Hugh Jennifer John John Mickel Royce Tom |
| --- |

**SELECT TOP**

The **SELECT TOP** is used to return number of data. The SELECT TOP can be very useful for thousands of record. Following is the syntax of SELECT TOP:

**Syntax:**

```
SELECT column_name
FROM name_of_table
LIMIT number;
```

**Example:**

```
SELECT *
FROM student_info
LIMIT 2;
```

**Output:**

| \| 12ST14 \| John \| Paris \| 232688 45 \| \| \| \| \| --- \| --- \| --- \| --- \| --- \| --- \| --- \| \| \| \| \| \| \| \| \| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| \| \| \| \| \| \| \| \| \| \| |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| 12ST14 | John | Paris | 232688 45 |  |  |  |
|  |  |  |  |  |  |  |
| 12ST10 | Royce | Argentina | 457912 34 |  |  |  |
|  |  |  |  |  |  |  |

**LIKE**

The LIKE is used with WHERE clause to search for a specific pattern. Following is the syntax:

```
SELECT column_name1
FROM name_of_table
WHERE column_name LIKE pattern;
```

## Example:

```
SELECT * FROM student_info
WHERE address LIKE  'a%';
```

**Output:**

| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| --- \| --- \| --- \| --- \| \| 12ST13 \| Hugh \| Luanda \| 2974789 34 \| \| \| \| \| \| |  |  |  |
| --- | --- | --- | --- |
| 12ST10 | Royce | Argentina | 457912 34 |
| 12ST13 | Hugh | Luanda | 2974789 34 |
|  |  |  |  |

**Wildcards**

**Wildcard**are used with LIKE operator. These wildcard are used to search data within a table. Following is the example of wildcard:

**Example:**

```
SELECT * FROM student_info
WHERE name LIKE  'e%';
```

**Output:**

| \| 12ST10 \| Royce \| Argentina \| 457912 34 \| \| --- \| --- \| --- \| --- \| |  |  |  |
| --- | --- | --- | --- |
| 12ST10 | Royce | Argentina | 457912 34 |

**IN**

The **IN** operator enable you to specify [multiple values](https://www.mindstick.com/forum/399/how-to-insert-multiple-values-selected-in-checkbox-in-database). Following is the example of wildcard:

**Syntax**

```
SELECT column_name
FROM name_of_table
WHERE column_name IN (value1,value2,...);
```

**Example:**

```
SELECT * FROM student_info
WHERE address IN ('Paris','London');
```

**Output**

| \| 12ST14 \| John \| Paris \| 232688 45 \| \| \| \| \| \| --- \| --- \| --- \| --- \| --- \| --- \| --- \| --- \| \| 12ST11 \| Mickel \| London \| 56276 45 \| \| \| \| \| \| \| \| \| \| \| \| \| \| |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 12ST14 | John | Paris | 232688 45 |  |  |  |  |
| 12ST11 | Mickel | London | 56276 45 |  |  |  |  |
|  |  |  |  |  |  |  |  |

NOTE: BETWEEN, Aliases, Joins, Inner Join, Left Join, Right Join, Full Join, Union, Select Into, [Insert Into Select](https://www.mindstick.com/interview/23338/the-sql-insert-into-select-statement), etc queries are discussed in next blog.

---

Original Source: https://www.mindstick.com/blog/11168/introduction-to-sql

Copyright © MindStick Software Pvt. Ltd. This Markdown version is provided for developers, AI systems, and offline reading.