All articles: Data Manipulation Language (DML)

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Using Lock Hints in SQL Server – Querychat
Locking hints in SQL Server are included in the general category of table hints that specified in the FROM clause, after the name of the table to which should be applied WITH([HINTS]). It is used to ensure data consistency and control concurrency in the Database table. The article explains how...
SQL Server generate GUID using NEWID() function – Querychat
GUID is a 16 byte binary SQL Server data type that is globally unique across tables, databases, and servers. The term GUID stands for Global Unique Identifier and it is also known as  UNIQUEIDENTIFIER. The data type of GUID is UNIQUEIDENTIFIER in SQL Server. To create a GUID in SQL...
How to convert rows to columns in MySQL – Querychat
Transposing SQL tables or converting rows to columns can be very useful especially when we want to generate some kind of special reports. In this article, we are going to study a special report in which we are going to transpose rows to columns. To achieve this, we will use...
SQL Server LEN() vs DATALENGTH() – QueryChat
The SQL Server LEN() function returns the length of a string, while the DATALENGTH() function returns the number of bytes used to represent an expression. In this article, we will compare and explore the use cases of DATALENGTH() and LEN() function with proper examples. SQL Server LEN() vs DATALENGTH() -...
How to import xml data into MySQL – Querychat
Importing data from an XML file into a MySQL database is very useful. In this article, we will learn how to import data from an XML file into a MySQL database using a few lines of PHP code. We will consider the XML nodes as the columns of the table...
MySQL Stored Function – Querychat
MySQL provides stored functions that contain a set of SQL statements to perform an operation and return the value of an expression. That can be a flexible way for us to manipulate and define data according to our needs. The article describes step-by-step how to create and utilize MySQL stored...
How to work with MySQL Loader – Querychat
MySQL provides commands that offers portability to our database since it allows us to export the result of our queries to a file. This file can serve as a backup, or we can also import it again either in our database or in any other MySQL database (portability). We are...
MySQL job scheduling – Querychat
There are two ways to run automatic processes in MySQL. One option is through the triggers and the other option through the events. The difference between triggers and events is that triggers are programmed to run automatically when an action occurs in a specific table. For example before/after insert a...
MySQL TRUNCATE statements and example – Querychat
There may arise a need, during the development or operations of MySQL database, to wipe out all the data in a table or set of tables. To achieve this MySQL has (like many other relational databases) the following methods: Issue a DELETE statement against the database table. Issue a DROP...
Mysql UPDATE statements and examples – Querychat
UPDATE is a Data Manipulation Language (DML) statement that modifies rows in a table. In this article, we will learn how to use the MySQL Update Statement in the database. An update statement is used to change or update a record in the table. The following are the statement is...
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