General MySQL Oracle SQL Server

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Ways to End the Current Transaction in Oracle
How To End the Current Transaction in Oracle? There are several ways the current transaction can be ended: Running the COMMIT statement will explicitly end the current transaction. Running the ROLLBACK statement will explicitly end the current transaction. Running any DDL statement will implicitly e... 2019-09-04, 3161🔥, 0💬

Difference between CHAR and VARCHAR in MySQL
What Are the Differences between CHAR and VARCHAR in MySQL? CHAR and VARCHAR are both ASCII character data types by default. But they have the following major differences: CHAR stores values in fixed lengths. Values are padded with space characters to match the specified length. VARCHAR stores value... 2018-01-19, 3160🔥, 0💬

Comments in SQL Server Transact-SQL Statements
How to enter comments in SQL Server Transact-SQL statements? There are 2 ways to enter comments within Transact-SQL statements: Starting comments with two dashes "--": Everything between "--" and the end of the line is treated as a comment. Entering comments between "/*" and "*/": Everything between... 2017-05-29, 3159🔥, 0💬

Determining Data Types of View Columns in SQL Server
How Column Data Types Are Determined in a View in SQL Server? When you define a view, its columns are defined through a list of expressions in the underlying SELECT statement. Their data types will be determined implicitly by the expressions. For example, if the column expression is a column name of... 2016-11-03, 3158🔥, 0💬

PS_CURRENT_THREAD_ID() - PS Thread ID of Current Connect
How to obtain the performance schema thread id of the current connection using the PS_CURRENT_THREAD_ID() function? PS_CURRENT_THREAD_ID() is a MySQL built-in function that returns the performance schema thread id of the current connection. For example: SELECT PS_CURRENT_THREAD_ID(); -- +-----------... 2025-02-16, 3156🔥, 0💬

Define a Cursor Variable in Oracle
How To Define a Cursor Variable in Oracle? To define cursor variable, you must decide which REF CURSOR data type to use. There are 3 ways to select a REF CURSOR data type: Define your own specific REF CURSOR types using the TYPE ... RETURN statement. Define your own generic REF CURSOR type using the... 2018-07-18, 3156🔥, 0💬

Rename an Existing Column in a Table in MySQL
How To Rename an Existing Column in a Table in MySQL? If you have an existing column in a table and you want to change the column name, you can use the "ALTER TABLE ... CHANGE" statement. This statement allows you to change the name of a column, and its definition. The tutorial script below gives yo... 2018-03-04, 3156🔥, 0💬

Understanding SQL DML Statements for Oracle
Where to find answers to frequently asked questions on SQL DML Statements for Oracle. I want insert and delete data in tables. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SQL DML Statements for Oracle. Clear answers are provided with tutorial ... 2020-02-07, 3155🔥, 0💬

Deleting Multiple Rows from a Table in MySQL
How To Delete Multiple Rows from a Table in MySQL? You can delete multiple rows from a table in the same way as deleting a single row, except that the WHERE clause will match multiple rows. The tutorial exercise below deletes 3 rows from the fyi_links table: mysql&gt; SELECT id, url, notes, coun... 2018-01-08, 3154🔥, 0💬

"mysqld" Command Line Options in MySQL
What Are the "mysqld" Command Line Options in MySQL? "mysqld" offers a big list of command line options. Here are some commonly used options: "--help" - Displays a short help message on how to use "mysqld". "--verbose --help" - Displays a long help messages on how to use "mysqld". "--console" - Spec... 2017-12-04, 3154🔥, 0💬

"CREATE USER" Statements - Creating a User in SQL Server
How to create a user to access a database using "CREATE USER" statements in SQL Server? This is the second tutorial of a quick lesson on creating login and configure users for databases with Transact-SQL statements. Granting a user access to a database involves three steps. First, you create a login... 2016-11-27, 3152🔥, 0💬

Show All Indexes in Your Schema in Oracle
How To List All Indexes in Your Schema in Oracle? If you log in with your Oracle account, and you want to get a list of all indexes in your schema, you can get it through the USER_INDEXES view with a SELECT statement, as shown in the following SQL script: SELECT index_name, table_name, uniqueness FR... 2019-05-01, 3151🔥, 0💬

odbc_errormsg() - Retrieving ODBC Error Messages
How To Retrieve Error Messages using odbc_errormsg()? When you call odbc_exec() to execute a SQL statement, and the execution failed on the SQL Server, you can use odbc_error() and odbc_errormsg() to retrieve the error code and error messages. The tutorial script below shows you a good example: &... 2024-06-30, 3150🔥, 0💬

Understanding SQL DDL Statements for Oracle
Where to find answers to frequently asked questions on SQL DDL Statements for Oracle? I want to start creating tables. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SQL DDL Statements for Oracle. Clear answers are provided with tutorial exercise... 2020-02-29, 3145🔥, 0💬

Name Query Output Columns in Oracle
How To Name Query Output Columns in Oracle? Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example: SQL&gt; SELECT department_id... 2019-09-27, 3145🔥, 2💬

💬 2019-09-19 Aninda mahadev: Good Tutorial!!!

Query with a Full Outer Join in Oracle
How To Write a Query with a Full Outer Join in Oracle? If you want to query from two tables with a full outer join, you can use the FULL OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a full outer join from two tables: departments and employees. The join conditi... 2019-10-18, 3142🔥, 0💬

Turn On and Off Recycle Bin for the Session in Oracle
How To Turn On or Off Recycle Bin for the Session in Oracle? If you want to control the recycle bin feature in your own session, you can use the ALTER SESSION statement to turn on or off. Here is an example SQL script: SQL&gt; connect HR/fyicenter Connected. SQL&gt; SELECT COUNT(*) FROM recy... 2019-05-10, 3142🔥, 0💬

Rebuild an Index in Oracle
How To Rebuild an Index in Oracle? If you want to rebuild an index, you can use the "ALTER INDEX ... REBUILD statement as shown in the following SQL script: SELECT index_name, table_name, uniqueness FROM USER_INDEXES WHERE table_name = 'EMPLOYEES'; INDEX_NAME TABLE_NAME UNIQUENES -------------------... 2019-04-17, 3141🔥, 0💬

Test NULL Values in Oracle
How To Test NULL Values in Oracle? There ate two special comparison operators you can use on NULL values: "variable IS NULL" - Returns TRUE if the variable value is NULL. "variable IS NOT NULL" - Return TRUE if the variable value is not NULL. The following sample script shows you examples of compari... 2018-07-13, 3141🔥, 0💬

Verify MySQL Server Status in MySQL
How Do You Know If Your MySQL Server Is Alive in MySQL? If you want to know whether your MySQL server is alive, you can use the "mysqladmin" program in a command window as shown in the following tutorial: &gt;cd \mysql\bin &gt;mysqladmin -u root ping mysqld is alive The "mysqld is alive" mes... 2018-06-06, 3138🔥, 0💬

"DROP" Statements - Deleting database objects in SQL Server
How to delete database objects with "DROP" statements in SQL Server? To remove all database objects created by previous tutorials, you could just delete the database. However, in this tutorial, you will go through the steps to reverse every action you took doing the tutorial. Removing permissions an... 2016-11-27, 3137🔥, 0💬

Mixing Group Functions with Non-group Selection Fields in SQL Server
Can Group Functions Be Mixed with Non-group Selection Fields in SQL Server? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of inva... 2016-10-25, 3135🔥, 0💬

ALTER TABLE - Delete a Column 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... 2020-02-20, 3134🔥, 0💬

Query with an Inner Join in Oracle
How To Write a Query with an Inner Join in Oracle? 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 following query returns output with an inner join from two tables: employees and departments. The join condition is that the de... 2019-10-27, 3134🔥, 0💬

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General MySQL Oracle SQL Server