All articles: Data Query Language (DQL)

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SQL Quick Reference Guide – Querychat
If we are new to SQL, SQL Quick Reference Guide will help us understand all basics within a short time. All 25 patterns of syntax in the SQL Quick Reference Guide will cover most of the basics in MySQL. All examples in this article can be executed in both SQL...
Syntax in SQL – Querychat
If you are new to SQL this article will help you understand the main syntax within a short time. All 6 patterns of syntax will cover most of the basics in MySQL. All examples in this article can be executed in both SQL Server and MySQL. Six patterns of syntax...
How to work with MS Access DATEADD function – Querychat
In this article, we will learn how to use the DATEADD function in MS Access with some practical examples. First, let's create a disposable_product table on which we will build our queries. The table will have the following structure and data: CREATE TABLE `disposable_product` (   `ID` integer NOT NULL,...
How to divide, multiply and get the module in SQL Server – Querychat
In this article, we will learn how the SQL Server divide, multiply, and modulo operators work. For this, we will use a Phone table with the following structure and data: CREATE TABLE [dbo].[phone]( [id] [int] NULL, [name] [varchar](30) NULL, [model] [varchar](20) NULL, [serie] [varchar](10) NULL, [price] [float] NULL, [stock] [int]...
Summarize Data for Each Column in SQL – Querychat
In this article, we are going to learn how to get the SQL summary of data in each column using MAX, MIN, AVG, COUNT, and SUM functions. Examples are supported for both SQL Server & MySQL. MAX/MIN function returns the maximum/minimum of a column.  AVG function returns the column average. ...
Using ISNULL in SQL – Querychat
In this article, we are going to learn about the ISNULL() function to replace a null with a given value in SQL. Real examples are included to overcome problems in SQL Server & MySQL. ISNULL() Function The ISNULL() function is given in the following format.  Syntax SELECT ISNULL(Column,  Value)   Table...
How to create and search indexes in Oracle – Querychat
This article discusses how we can create indexes, search and drop the existing indexes on Oracle Tables. Let’s first define what are indexes. Indexes are those database structures that help in faster accessing of data stored in a table column(s). For example, consider an Employee Table with around 1 million...
Using Parentheses in SQL – Querychat
In this article, we are going to learn how to use round brackets or parentheses in logical operators, mathematical solutions, value returns & various operations in SQL. All examples in this article can be executed in both SQL Server and MySQL. Refer to the below table for the following examples....
Using CONCAT & Split a String in SQL – Querychat
In this article, we are going to learn about how we use the CONCAT() function to add values or columns together. In addition, we will also take a look at how to split a string using STRING_SPLIT() and SUBSTRING() functions. Examples in this article are available in both SQL Server...
RTRIM, LTRIM & TRIM Functions in SQL Server – Querychat
In this article we are going to learn how to use RTRIM(), LTRIM() and TRIM() functions in SQL Server to remove ending spaces, outer spaces or characters of a column in SQL. Examples are also included in this article.  Refer to the below table for the following examples. Imagine the...
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