General MySQL Oracle SQL Server

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What Is Index in MySQL
What Is Index in MySQL? An index is a single column or multiple columns defined to have values pre-sorted to speed up data retrieval speed.   ⇒ What Is View in MySQL ⇐ What Is Foreign Key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2258🔥, 0💬

Use Subqueries in the FROM Clause in Oracle
How To Use Subqueries in the FROM Clause in Oracle? 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. The following statement shows you how to use a subquery as base ... 2019-09-27, 2257🔥, 0💬

What Is "mysqlshow" Command in MySQL
What Is "mysqlshow" in MySQL? "mysqlshow" is a command-line interface for end users to see information on tables and columns. Here are some sample commands supported by "mysqlshow": "mysqlshow" - Shows all the databases. "mysqlshow databaseName" - Shows all the tables in the specified database. "mys... 2018-02-28, 2257🔥, 0💬

Deleting All Rows with TRUNCATE TABLE Statement in SQL Server
How To Delete All Rows with TRUNCATE TABLE Statement in SQL Server? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise... 2016-10-30, 2257🔥, 0💬

Commit the Current Transaction in Oracle
How To Commit the Current Transaction in Oracle? If you have used some DML statements updated some data objects, and you want to have the updates to be permanently recorded in the database, you can use the COMMIT statement. It will make all the database changes made in the current transaction become... 2019-09-04, 2256🔥, 0💬

Use an Explicit Cursor without OPEN Statements in Oracle
How To Use an Explicit Cursor without OPEN Statements in Oracle? If you want to open a cursor and loop through its data rows in quick way, you can use the FOR ... IN ... LOOP statement in the same way as the implicit cursor. The following tutorial exercise gives you a good example: CREATE OR REPLACE... 2018-04-07, 2254🔥, 0💬

Entering Date and Time Values in SQL Server
How To Enter Date and Time values in SQL Server Transact-SQL? Transact-SQL does not support date and time literals. If you want to enter date and time values, you have to use character string literals and rely implicit casting rules to convert them into date and time values. When casting character s... 2017-04-15, 2254🔥, 0💬

Retrieve Data from an Explicit Cursor in Oracle
How To Retrieve Data from an Explicit Cursor in Oracle? If you have a cursor opened ready to use, you can use the FETCH ... INTO statement to retrieve data from the cursor into variables. FETCH statement will: Retrieve all the fields from the row pointed by the current cursor pointer and assign them... 2018-07-22, 2253🔥, 0💬

Select All Columns of All Rows in Oracle
How To Select All Columns of All Rows from a Table in Oracle? The simplest query statement is the one that selects all columns of all rows from a table: "SELECT * FROM table_name;". The (*) in the SELECT clause tells the query to return all columns. The tutorial exercise below gives you a good examp... 2019-12-19, 2250🔥, 0💬

Define a Variable to Match Column Data Type in Oracle
How To Define a Variable to Match a Table Column Data Type in Oracle? If you have a table, and want to define some variables to have exactly the same data types as some columns in that table, you can use table_name.column_name%TYPE as data types to define those variables. The tutorial sample below s... 2018-08-14, 2250🔥, 0💬

Create a Table Index in Oracle
How To Create a Table Index in Oracle? If you have a table with a lots of rows, and you know that one of the columns will be used often a search criteria, you can add an index for that column to in improve the search performance. To add an index, you can use the CREATE INDEX statement as shown in th... 2019-05-01, 2248🔥, 0💬

What Is Row in MySQL
What Is Row in MySQL? A row is a unit of data with related data items stored as one item in one column in a table.   ⇒ What Is Primary key in MySQL ⇐ What Is Column in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-15, 2247🔥, 0💬

Converting Numeric Expressions from One Data Type to Another in SQL Server
How To Convert a Numeric Expression from One Data Type to Another in SQL Server Transact-SQL? There are 4 ways to convert a numeric expression from one data type to another data type: Implicit conversion by arithmetic operations - When arithmetic operations are performed on expressions of different ... 2017-03-27, 2247🔥, 0💬

Omit Columns in INSERT Statements in Oracle
How To Omit Columns with Default Values in INSERT Statement in Oracle? If you don't want to specify values for columns that have default values, or you want to specify values to columns in an order different than how they are defined, you can provide a column list in the INSERT statement. If a colum... 2020-01-29, 2246🔥, 0💬

Supported Transaction Isolation Levels in Oracle
What Are Transaction Isolation Levels Supported by Oracle in Oracle? Oracle supports two transaction isolation levels: READ COMMITTED (the default option). If the transaction contains DML that requires row locks held by another transaction, then the DML statement waits until the row locks are releas... 2019-08-19, 2246🔥, 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, 2244🔥, 0💬

Update a Table Row with a RECORD in Oracle
How To Update a Table Row with a RECORD in Oracle? If you have a RECORD variable with data fields matching a table structure, you can update a row in this table with this RECORD variable using the UPDATE ... SET ROW statement as shown in the sample script below: CREATE TABLE emp_temp AS SELECT * FRO... 2018-08-14, 2243🔥, 0💬

Deleting All Rows in a Table in MySQL
How To Delete All Rows in a Table in MySQL? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise shows you a good exampl... 2018-01-08, 2241🔥, 0💬

Report View in SQL Developer in Oracle
What Is the Reports View in Oracle SQL Developer in Oracle? The Reports view lets you browse database information that organized by the server as special views. Information can be browsed include: Database parameters Storage information Session information Cursors Data objects User accounts Security... 2018-10-08, 2240🔥, 0💬

Transaction Committed when DDL Statement Executed in MySQL
What Happens to the Current Transaction If a DDL Statement Is Executed in MySQL? If a DDL statement is executed, the current transaction will be committed and ended. All the database changes made in the current transaction will become permanent. This is called an implicit commit by a DDL statement. ... 2016-10-17, 2240🔥, 0💬

Who Is the Owner of a Schema in SQL Server
Who Is the Owner of a Schema in SQL Server? When you create a schema in a database, SQL Server will assign a owner (a database user) to this schema. If your login name is mapped to the owner of a schema at the database level, you have the full permission on all objects in this schema. The following ... 2016-10-22, 2239🔥, 0💬

Show All User Accounts in the Database in Oracle
How To Get a List of All User Accounts in the Database in Oracle? If you don't like to use a SELECT statement to get a list of all user accounts in the current database, you can use the Reports view to do this as shown in the following tutorial example. You need to connect to the server as SYSTEM to... 2019-01-26, 2237🔥, 0💬

Use "mysql" to Run SQL Statements in MySQL
How To Use "mysql" to Run SQL Statements in MySQL? If you want to run SQL statement to your server with "mysql", you need to start "mysql" and enter your SQL statement at the "mysql" prompt. Here is a good tutorial exercise that shows you how to run two SQL statements with "mysql": &gt;cd \mysql... 2018-02-28, 2237🔥, 0💬

"CREATE TRIGGER" - Creating a DDL Trigger in SQL Server
How To Create a DDL Trigger using "CREATE TRIGGER" Statements in SQL Server? A DDL trigger is defined to handle a DDL statement event, like create, alter and drop tables, views, indexes, etc. DDL triggers can be used to generate warning messages on database object changes. The format of creating a D... 2016-10-22, 2237🔥, 0💬

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General MySQL Oracle SQL Server