General MySQL Oracle SQL Server

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Drop an Existing Index in MySQL
How To Drop an Existing Index in MySQL? If you don't need an existing index any more, you should delete it with the "DROP INDEX indexName ON tableName" statement. Here is an example SQL script: mysql&gt; DROP INDEX tip_subject ON tip; Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0... 2018-02-14, 801👍, 0💬

Create an Index for a Given Table in MySQL
How To Create an Index for a Given Table in MySQL? If you have a table with a lots of rows, and you know that one of the columns will be used often as a search criteria, you can add an index for that column to improve the search performance. To add an index, you can use the "CREATE INDEX" statement ... 2018-02-14, 754👍, 0💬

Drop an Existing Table in MySQL
How To Drop an Existing Table in MySQL? If you want to delete an existing table and its data rows, you can use the "DROP TABLE" statement as shown in the tutorial script below: mysql&gt; SELECT * FROM tipBackup; +----+-------------+---------- ---------------+-------------+| id | subject | descri... 2018-02-14, 731👍, 0💬

Rename an Existing Table in MySQL
How To Rename an Existing Table in MySQL? If you want to rename an existing table, you can use the "ALTER TABLE ... RENAME TO" statement. The tutorial script below shows you a good example: mysql&gt; ALTER TABLE tip RENAME TO faq; Query OK, 0 rows affected (0.01 sec) mysql&gt; SELECT * FROM ... 2018-02-14, 702👍, 0💬

Running "mysql" Commands from a Batch File in MySQL
How To Run "mysql" Commands from a Batch File in MySQL? If you have group of "mysql" commands that need to be executed repeatedly, you can put them into a file, and run them from the file in "mysql" batch mode. Here is a batch file, \temp\links.sql, contains following commands: USE test; INSERT INTO... 2018-02-08, 874👍, 0💬

Non-Standard SQL Commands in MySQL
What Are the Non-Standard SQL Commands Supported by "mysql" in MySQL? There are many non-standard SQL commands that are supported by "mysql". Here is short list of some commonly used commands: "SHOW infoName" - Shows basic information of based on the specified information name. "SHOW infoName" - Sho... 2018-02-08, 861👍, 0💬

Returning Query Output in HTML Format in MySQL
How To Return Query Output in HTML Format in MySQL? By default, "mysql" returns query output in text table format. If you want to receive query output in HTML format, you need to use the "-H" command option. Here is a good tutorial exercise: &gt;cd \mysql\bin &gt;mysql -u root -H test mysql&... 2018-02-08, 775👍, 0💬

Getting Help Information from the Server in MySQL
How To Get Help Information from the Server in MySQL? While you are at the "mysql&gt;" prompt, you can get help information from the server by using the "HELP" command. The tutorial exercise below shows sevearal examples: &gt;cd \mysql\bin &gt;mysql -u root mysql&gt; HELP; ... List o... 2018-02-08, 775👍, 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, 757👍, 0💬

INSERT, UPDATE and DELETE Statements in MySQL
Where to find answers to frequently asked questions on INSERT, UPDATE and DELETE Statements in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on INSERT, UPDATE and DELETE Statements in MySQL. Clear answers are provided with tutorial exercises... 2018-01-24, 1412👍, 0💬

Drop an Existing View in MySQL
How To Drop an Existing View in MySQL? If you have an existing view, and you don't want it anymore, you can delete it by using the "DROP VIEW viewName" statement as shown in the following script: mysql&gt; DROP VIEW faqComment; Query OK, 0 rows affected (0.00 sec) mysql&gt; SELECT * FROM faq... 2018-01-24, 723👍, 0💬

Creating a Test Table in MySQL
How To Create a Testing Table in MySQL? If you want to practice DML statements, like INSERT, UPDATE and DELETE, you should create a testing table. The tutorial exercise shows you a good example: mysql&gt; CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url VARCHAR(80) NOT NULL, notes VARCHAR(102... 2018-01-24, 715👍, 0💬

Create a New View in MySQL
How To Create a New View in MySQL? You can create a new view based on one or more existing tables by using the "CREATE VIEW viewName AS selectStatement" statement as shown in the following script: mysql&gt; CREATE TABLE comment (faqID INTEGER, message VARCHAR(256)); Query OK, 0 rows affected (0.... 2018-01-24, 710👍, 0💬

What Are DML Statements in MySQL
What Are DML Statements in MySQL? DML (Data Manipulation Language) statements are statements to change data values in database tables. The are 3 primary DML statements: INSERT - Inserting new rows into database tables. UPDATE - Updating existing rows in database tables . DELETE - Deleting existing r... 2018-01-24, 685👍, 0💬

Difference between CHAR and NCHAR in MySQL
What Are the Differences between CHAR and NCHAR in MySQL? Both CHAR and NCHAR are fixed length string data types. But they have the following differences: CHAR's full name is CHARACTER. NCHAR's full name is NATIONAL CHARACTER. By default, CHAR uses ASCII character set. So 1 character is always store... 2018-01-19, 862👍, 0💬

Difference between BINARY and VARBINARY in MySQL
What Are the Differences between BINARY and VARBINARY in MySQL? Both BINARY and VARBINARY are both binary byte data types. But they have the following major differences: BINARY stores values in fixed lengths. Values are padded with 0x00. VARBINARY stores values in variable lengths. Values are not pa... 2018-01-19, 842👍, 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, 829👍, 0💬

Date and Time Data Types in MySQL
What Are Date and Time Data Types in MySQL? MySQL supports the following date and time data types: DATE - A date in the range of '1000-01-01' and '9999-12-31'. Default DATE format is "YYYY-MM-DD". DATETIME - A date with the time of day in the range of '1000-01-01 00:00:00' and '9999-12-31 23:59:59'.... 2018-01-19, 812👍, 0💬

Numeric Data Types in MySQL
What Are Numeric Data Types in MySQL? MySQL supports the following numeric data types: BIT(n) - An integer with n bits. BOOL same as BOOLEAN - Boolean values stored in 1 bit. TINYINT - A small integer stored in 1 byte. SMALLINT - A small integer stored in 2 bytes. MEDIUMINT - A medium integer stored... 2018-01-19, 740👍, 0💬

Using Column Default Values in MySQL
How To Specify Default Values in INSERT Statement in MySQL? If a column is defined with a default value in a table, you can use the key word DEFAULT in the INSERT statement to take the default value for that column. The following tutorial exercise gives a good example: mysql&gt; INSERT INTO fyi_... 2018-01-16, 858👍, 0💬

Omitting Columns in INSERT Statements in MySQL
How To Omit Columns with Default Values in INSERT Statement in MySQL? 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 column... 2018-01-16, 849👍, 0💬

Violation of Unique Value Constraint in MySQL
What Happens If Unique Value Constraints Are Violated in MySQL? If you are inserting a new record that has values violating a unique constraint, you will get an error. Note that primary key column has a unique value constraint by default. The following tutorial exercise gives you some good examples:... 2018-01-16, 761👍, 0💬

Inserting a New Row into a Table in MySQL
How To Insert a New Row into a Table in MySQL? To insert a new row into a table, you should use the INSERT INTO statement with values specified for all columns as shown in the following example: mysql&gt; INSERT INTO fyi_links VALUES (101, 'dev.fyicenter.com', NULL, 0, '2006-04-30'); Query OK, 1... 2018-01-16, 743👍, 0💬

Insert Multiple Rows with 1 INSERT Statement in MySQL
How To Insert Multiple Rows with One INSERT Statement in MySQL? If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. The following tutorial exercise gives a good exa... 2018-01-16, 696👍, 0💬

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General MySQL Oracle SQL Server