General MySQL Oracle SQL Server

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What Is a READ WRITE Transaction in Oracle
What Is a READ WRITE Transaction in Oracle? A READ WRITE transaction is a transaction in which the read consistency is set at the statement level. In a READ WRITE transaction, a logical snapshot of the database is created at the beginning of the execution of each statement and released at the end of... 2019-08-23, 3393🔥, 0💬

Use SYS Account to Connect to the Server in Oracle
How To Connect to the Server with User Account: SYS in Oracle? SYS is a very special user account. It has been associated with the highest privilege call SYSDBA. Normally, you should not connect to the server with SYS. But if you want to use it, you need to use a special connect command: &gt;cd ... 2019-07-21, 3393🔥, 0💬

Delete a Column in an Existing Table in Oracle
How To Delete a Column in an Existing Table in Oracle? If you have an existing column in a table and you need that column any more, you can delete it with ALTER TABLE ... DROP COLUMN statement. Here is an example SQL script: SQL&gt; CREATE TABLE emp_dept_90 2 AS SELECT * FROM employees WHERE dep... 2019-05-25, 3391🔥, 0💬

Default Collation in SQL Server Transact-SQL
How To Find Out What Is the Default Collation in SQL Server Transact-SQL? The default collation of a database comes from the server if you are not using the COLLATE clause in the CREATE DATABASE statement. If you are not using the COLLATE clause for character string column, it will use the default c... 2017-05-13, 3390🔥, 0💬

What Is RollBack in MySQL
What Is Rollback in MySQL? Rollback is a way to terminate a transaction with all database changes not saving to the database server.   ⇒ MySQL Database Tutorials ⇐ What Is Commit in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2016-10-16, 3390🔥, 0💬

"DROP USER" - Deleting a Database User in SQL Server
How To Delete an Existing Database User in SQL Server? If you don't want to keep a database user any more, you should delete the user by using the "DROP USER" statement. This tutorial exercise shows how to delete "Dba_User": -- Login with "sa" USE FyiCenterData; GO DROP USER Dba_User; GO -- List all... 2022-01-24, 3389🔥, 0💬

LAST_INSERT_ID() - Last Value of AUTO_INCREMENT Column
How to obtain the last inserted value of an AUTO_INCREMENT column using the LAST_INSERT_ID() function? LAST_INSERT_ID() is a MySQL built-in function that returns the last inserted value of an AUTO_INCREMENT column. For example: CREATE TABLE MyTable (id INTEGER AUTO_INCREMENT, comment CHAR(80), PRIMA... 2025-04-11, 3387🔥, 0💬

What Is SQL Standard in Oracle
What Is SQL Standard in Oracle? SQL, SEQUEL (Structured English Query Language), is a language for RDBMS (Relational Database Management Systems). SQL was developed by IBM Corporation. SQL became an ANSI standard, called SQL-87, in 1986. ISO made a major revision, called SQL-92, in 1992. The latest ... 2020-05-29, 3387🔥, 0💬

ALTER TABLE - Add a New Column in Oracle
How To Add a New Column to an Existing Table in Oracle? If you have an existing table with existing data rows, and want to add a new column to that table, you can use the ALTER TABLE ... ADD statement to do this. Here is an example script: SQL&gt; connect HR/fyicenter Connected. SQL&gt; CREA... 2020-02-29, 3384🔥, 0💬

SQL Server Connection Protocols
What connection protocols are supported by SQL Server? SQL Server supports the following connection protocols: 1. TCP/IP (Transmission Control Protocol/Internet Protocol) - This is the most commonly used protocols to connect to SQL Server databases. It allow client tools or application programs on a... 2024-08-14, 3383🔥, 0💬

Transaction Rollback When Session Killed in Oracle
What Happens to the Current Transaction If the Session Is Killed in Oracle? If a session is killed by the DBA, the current transaction in that session will be rolled back and ended. All the database changes made in the current transaction will be removed. This is called an implicit rollback when ses... 2019-08-23, 3383🔥, 0💬

Analyze Tables with "mysqlcheck" Command in MySQL
How To Analyze Tables with "mysqlcheck" in MySQL? If you want analyze tables with "mysqlcheck", you need to use the "--analyze" option. The following tutorial exercise shows you how to analyze all tables in "mysql" database: &gt;cd \mysql\bin &gt;mysqlcheck -u root --analyze mysql mysql.colu... 2018-02-28, 3383🔥, 0💬

What Is ODBC in Oracle
What Is Open Database Communication (ODBC) in Oracle? ODBC, Open Database Communication, a standard API (application program interface) developed by Microsoft for Windows applications to communicate with database management systems. Oracle offers ODBC drivers to allow Windows applications to connect... 2020-05-15, 3382🔥, 0💬

Differences between CHAR and VARCHAR in Oracle
What Are the Differences between CHAR and VARCHAR2 in Oracle? The main differences between CHAR and VARCHAR2 are: CHAR stores values in fixed lengths. Values are padded with space characters to match the specified length. VARCHAR2 stores values in variable lengths. Values are not padded with any cha... 2020-04-25, 3382🔥, 0💬

Calculating the Difference between Two Dates in MySQL
How To Calculate the Difference between Two Dates in MySQL? If you have two dates, and you want to know how many days between them, you can use the DATEDIFF(date1, date2) function as shown below: SELECT DATEDIFF(DATE('1997-02-28'), DATE('1997-03-01')) FROM DUAL; -1   ⇒ Calculating the Difference bet... 2017-12-26, 3381🔥, 0💬

Oracle Built-in Data Types in Oracle
What Are the Oracle Built-in Data Types in Oracle? There are 20 Oracle built-in data types, divided into 6 groups: Character Datatypes - CHAR, NCHAR, NVARCHAR2, VARCHAR2 Number Datatypes - NUMBER, BINARY_FLOAT, BINARY_DOUBLE Long and Row Datatypes - LONG, LONG RAW, RAW Datetime Datatypes - DATE, TIM... 2020-05-29, 3380🔥, 0💬

Show All Columns of an Existing Table in MySQL
How To Get a List of Columns in an Existing Table in MySQL? If you have an existing table, but you don't remember what are the columns used in the table, you can use the "SHOW COLUMNS FROM tableName" command to get a list of all columns of the specified table. You can also use the "DESCRIBE tableNam... 2018-03-10, 3380🔥, 0💬

What Is a Subquery in Oracle
What Is a Subquery in Oracle? A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The output of the subquery will be used in the final eval... 2019-09-27, 3378🔥, 0💬

Use Windows User to Connect to the Server in Oracle
How To Use Windows User to Connect to the Server in Oracle? During the installation process, 10g XE will create a special Windows user group called ORA_DBA, and put your Windows user into this group. Any Windows users in this group can be connected to Oracle server with SYSDBA privilege without any ... 2019-07-21, 3377🔥, 0💬

Rules on Arithmetic Operations in SQL Server
What Are Arithmetic Operators in SQL Server Transact-SQL? An arithmetic operator performs an arithmetic operation on two expressions of numeric data types. SQL Server supports 5 arithmetic operators: + (Add): Addition - (Subtract): Subtraction * (Multiply): Multiplication / (Divide): Division % (Mod... 2017-04-01, 3376🔥, 0💬

JSON_SCHEMA_VALIDATION_REPORT() - JSON Schema Validation Report
How to generate a validation report of a JSON value against a JSON schema using the JSON_SCHEMA_VALIDATION_REPORT( )function? JSON_SCHEMA_VALIDATION_REPORT( schema,json) is a MySQL built-in function that returns a validation report of a JSON value against a given JSON schema. The report itself is a ... 2024-11-23, 3370🔥, 0💬

Change Settings in Binary SPFile in Oracle
What To Do If the Binary SPFile Is Wrong for the Default Instance in Oracle? Let's say the SPFile for the default instance is a binary file, and some settings are wrong in the SPFile, like SGA setting is bellow 20MB, how do you change a setting in the binary file? This seems to be a hard task, becau... 2020-09-15, 3370🔥, 0💬

Working with Cursors in Oracle PL/SQL
Where to find answers to frequently asked questions on Working with Cursors in Oracle PL/SQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Working with Cursors in Oracle PL/SQL. Clear answers are provided with tutorial exercises on defining, op... 2018-02-01, 3369🔥, 0💬

Numeric Literals in Oracle
How To Write Numeric Literals in Oracle? Numeric literals can coded as shown in the following samples: SELECT 255 FROM DUAL -- An integer 255 SELECT -6.34 FROM DUAL -- A regular number -6.34 SELECT 2.14F FROM DUAL -- A single-precision floating point 2.14 SELECT -0.5D FROM DUAL -- A double-precision... 2020-04-14, 3368🔥, 0💬

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General MySQL Oracle SQL Server