General MySQL Oracle SQL Server

<< < … 37 38 39 40 41 42 43 44 45 46 47 … > >>   ∑:1365  Sort:Date

Rollback the Current Transaction in MySQL
How To Rollback the Current Transaction in MySQL? If you have used some DML statements updated some data objects, you find a problem with those updates, and you don't want those updates to be permanently recorded in the database, you can use the ROLLBACK command. It will remove all the database chan... 2016-10-17, 3129🔥, 0💬

Performing Comparison on Exact Numbers in SQL Server
How To Perform Comparison on Exact Numbers in SQL Server Transact-SQL? Comparison operations on exact numbers of data types: BIT, INT, NUMERIC, etc., are very easy to understand. Here are some simple examples: -- BIT value comparison DECLARE @x BIT, @y BIT; SET @x = 0; SET @y = 1; SELECT CASE WHEN @... 2017-01-21, 3128🔥, 0💬

Update Values on Multiple Rows in Oracle
How To Update Values on Multiple Rows in Oracle? If the WHERE clause in an UPDATE matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example: UPDATE fyi_links SET counts = 9, n... 2020-01-21, 3127🔥, 0💬

Query with an Inner Join in MySQL
How To Write a Query with an Inner Join in MySQL? If you want to query from two tables with an inner join, you can use the INNER JOIN ... ON clause in the FROM clause. The tutorial exercise below creates another testing table and returns output with an inner join from two tables: fyi_links and fyi.r... 2017-12-31, 3127🔥, 0💬

Using Subqueries in the FROM Clause in SQL Server
How To Use Subqueries in the FROM Clause in SQL Server? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. A subquery used in this way become a temporary table, and yo... 2016-10-29, 3127🔥, 0💬

Selecting Other User's Database in MySQL
Can You Select Someone Else Database in MySQL? If your MySQL server is provided by an Internet service company, they will provide you one database for your use only. There are many other databases on the server for other users. But your user account will have no privilege to select other databases. ... 2017-10-23, 3126🔥, 0💬

Create a New Table by Selecting Rows from Another Table in Oracle
How To Create a New Table by Selecting Rows from Another Table in Oracle? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the CREATE TABLE...AS SELECT statement to do this. Here is an example script: &... 2019-06-01, 3123🔥, 0💬

Read Consistency in Oracle in Oracle
How Does Oracle Handle Read Consistency in Oracle? Oracle supports two options for you on how to maintain read consistency: READ WRITE (the default option), also called statement-level read consistency. READ ONLY, also called transaction-level read consistency.   ⇒ What Is a READ WRITE Transaction i... 2019-08-23, 3122🔥, 0💬

Define an Explicit Cursor in Oracle
How To Define an Explicit Cursor in Oracle? An explicit cursor must be defined in the declaration part of a procedure or function with the CURSOR ... IS statement as shown in the following sample script: DECLARE CURSOR c_list IS SELECT * FROM countries; CURSOR t_list IS SELECT * FROM employees WHERE... 2018-07-22, 3122🔥, 0💬

Index Speeding Up SELECT Statements in SQL Server
Does Index Speed Up SELECT Statements in SQL Server? If you want to see the impact of indexes on SELECT statements, you can run the same SELECT statement on "fyi_links" and "fyi_links_indexed" tables. See the tutorial exercise below: USE FyiCenterData; GO -- Run SELECT on the table without indexes D... 2016-11-13, 3121🔥, 0💬

CREATE CLUSTERED INDEX - Adding Clustered Indexes in SQL Server
How To Create a Clustered Index in SQL Server? If there is no primary key in a table, you can add one clustered index to that table with CREATE CLUSTERED INDEX statement. The tutorial exercise below shows you how to create a clustered index: USE FyiCenterData; GO -- Drop the old table, if needed DRO... 2016-11-13, 3120🔥, 0💬

JSON_TYPE() - Detecting Type of JSON Value
How to detect the type of a JSON (JavaScript Object Notation) value using the JSON_TYPE() function? JSON_TYPE(json) is a MySQL built-in function that returns the data type of a JSON (JavaScript Object Notation) value. For example: SELECT JSON_TYPE('[]'), JSON_TYPE('{}'); -- +-----------------+------... 2025-03-12, 3119🔥, 0💬

Create a Test Table for DML Testing in Oracle
How To Create a Testing Table in Oracle? If you want to practice DML statements, you should create a testing table as shown in the script below: CREATE TABLE fyi_links (id NUMBER(4) PRIMARY KEY, url VARCHAR2(80) NOT NULL, notes VARCHAR2(1024), counts NUMBER, created DATE DEFAULT (sysdate)); Table cr... 2020-02-07, 3119🔥, 0💬

System Defined User Roles in Oracle
What Are the System Predefined User Roles in Oracle? Oracle 10g XE comes with 3 predefined roles: CONNECT - Enables a user to connect to the database. Grant this role to any user or application that needs database access. RESOURCE - Enables a user to create certain types of schema objects in his own... 2019-07-30, 3117🔥, 0💬

Ways to Join Two Tables in a Single Query in Oracle
How To Join Two Tables in a Single Query in Oracle? Two tables can be joined together in a query in 4 ways: Inner Join: Returns only rows from both tables that satisfy the join condition. Left Outer Join: Returns rows from both tables that satisfy the join condition, and the rest of rows from the fi... 2019-10-27, 3115🔥, 0💬

Use Group Functions in the SELECT Clause in Oracle
How To Use Group Functions in the SELECT Clause in Oracle? If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The following select statement returns 4 values ca... 2019-11-21, 3113🔥, 0💬

Using Regular Expression with REGEXP in MySQL
How To Use Regular Expression in Pattern Match Conditions in MySQL? If you have a pattern that is too complex for LIKE to handle, you can use the regular expression pattern condition: REGEXP. The following tutorial exercise provides you some good examples: SELECT 'FYICenter.com' REGEXP '.*fyi.*' FRO... 2018-03-24, 3113🔥, 0💬

DML Commands Supported in MySQL
How Many SQL DML Commands Are Supported by "mysql" in MySQL? There are 4 SQL Data Manipulation Language (DML) commands that are supported by "mysql". They are listed below with short descriptions: "INSERT INTO tableName ..." - Inserts new data rows into the specified table. "DELETE FROM tableName ..... 2018-02-08, 3113🔥, 0💬

Query with a Full Outer Join in MySQL
How To Write a Query with a Full Outer Join in MySQL? There is no way to do full outer join in MySQL. It does not support this feature at the current MySQL release.   ⇒ Inner Join with the WHERE Clause in MySQL ⇐ Query with a Right Outer Join in MySQL ⇑ SELECT Statements with JOIN and Subqueries in... 2017-09-28, 3113🔥, 0💬

Deleting a Table That Is Used by a View in SQL Server
What Happens If You Delete a Table That Is Used by a View in SQL Server? Assuming that you have a table which is used by a view, and you try to delete that table. SQL Server will let you delete the table without any trouble. But that view will become invalid. The tutorial exercise below shows you wh... 2016-11-04, 3112🔥, 0💬

Count Duplicated Values in a Column in Oracle
How To Count Duplicated Values in a Column in Oracle? If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAVING clause as shown in the following example. It re... 2019-11-21, 3110🔥, 0💬

Types of Execution Flow Control Statements in Oracle
What Are the Execution Control Statements in Oracle? PL/SQL supports three groups of execution control statements: IF Statements - Conditionally executes a block of statements. CASE Statements - Selectively executes a block of statements. LOOP Statements - Repeatedly executes a block of statements. ... 2018-11-17, 3109🔥, 0💬

Using Subqueries in the FROM Clause in MySQL
How To Use Subqueries in the FROM clause in MySQL? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. A subquery used in this way become a temporary table, and you mus... 2017-12-21, 3109🔥, 0💬

Renaming Database Names in SQL Server
How to rename databases in SQL Server? If don't like the name of a database, you can change it by using the "ALTER DATABASE" statement with the following syntax: ALTER DATABASE database_name MODIFY NAME = new_database_name The tutorial example below shows you how change the database name from "FyiCe... 2016-11-24, 3109🔥, 0💬

<< < … 37 38 39 40 41 42 43 44 45 46 47 … > >>   ∑:1365  Sort:Date

General MySQL Oracle SQL Server