What is – DML, DDL, DCL and TCL – Introduction

DML DML is abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, delete, insert and update data in database. Examples: SELECT, UPDATE, INSERT statements DDL DDL is abbreviation of Data Definition Language. It is used to create and modify the structure of database objects in database. Examples: CREATE, ALTER, DROP statements DCL DCL is abbreviation of Data Control Language. It is used to create roles, permissions, and referential integrity as well it is used to control access to database…

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Find Duplicate Values with SQL Script

Let’s assume that data has been entered in a table and now you want to find if a table column have duplicated values. Here is an SQL script to join data from one table for comparison purpose. The table must have a primary key column (unique column) and the second column for comparison. Here is a sample script: Details: – DWDOCID is the primary key column – AIXFlag, is just a fixed value (optional) – SAMPLEEN is the table…

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T/SQL Splint String/Text

One common task performed in database applications is given a full name, how can this be split into the first name and last name.  In this article, three different methods are discussed to perform this task using three different functions in SQL Server.  It is assumed in this article that the full name is just made up of one first name and one last name. Using SUBSTRING Function The first method is the use of the SUBSTRING string function,…

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T/SQL Generate Random Numbers

SQL Server has a built-in function that generates a random number, the RAND() mathematical function.  The RAND math function returns a random float value from 0 through 1.  It can take an optional seed parameter, which is an integer expression (tinyint, smallint or int) that gives the seed or start value. To use it, you can simply do a simple SELECT, as follows: SELECT RAND() AS The result generated by this SELECT statement is as follows (note that…

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UPDATE From SELECT Statement – Using JOIN in UPDATE Statement – Multiple Tables in Update Statement

In recent times I have seen a developer writing a cursor to update a table. When asked the reason was he had no idea how to use multiple tables with the help of the JOIN clause in the UPDATE statement. However, the easiest and the most clean way is to use JOIN clause in the UPDATE statement and use multiple tables in the UPDATE statement and do the task. Let us see the following example. We have two tables Table 1…

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MySQL TRIM() function

MySQL TRIM() function returns a string after removing all prefixes or suffixes from the given string. Syntax TRIM( str) Arguments Name Description BOTH Indicates that prefixes from both left and right are to be removed. LEADING Indicates that only leading prefixes are to be removed. TRAILING Indicates that only trailing prefixes are to be removed. remstr The string to be removed. FROM Keyword str The actual string from where remstr is to…

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