General MySQL Oracle SQL Server

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Writing Date and Time Literals in MySQL
How To Write Date and Time Literals in MySQL? MySQL offers a number of formats for you to use to enter date and time literals: ANSI standard format: "YYYY-MM-DD HH:MM:SS". Non-standard limiters. Like: "YYYY/MM/DD HH^MM^SS" or "YYYY.MM.DD HH-MM-SS". No limiters. Like: "YYYYMMDD" for a date or "HHMMSS... 2017-12-26, 2705🔥, 0💬

Turn on Binary Logs in MySQL
How To Turn on Binary Logs in MySQL? If you want MySQL to write binary logs to a file, you can use the "--log-bin=fileBaseName" option at the "mysqld" command line. The tutorial exercise below shows you a good example on how to use this option: &gt;cd \mysql\bin &gt;mkdir \mysql\logs &gt... 2017-11-29, 2702🔥, 0💬

Apply Filtering Criteria at Group Level in MySQL
How To Apply Filtering Criteria at Group Level in MySQL? If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. Note group functions can also be used in HAVING conditions. The following tut... 2017-10-16, 2702🔥, 0💬

VALIDATE_PASSWORD_STRENGTH() - Password Strength Test
How to test the strength of a password using the VALIDATE_PASSWORD_STRENGTH() function? VALIDATE_PASSWORD_STRENGTH(pas sword)is a MySQL built-in function that calculates the strength of a given password. It requires validate_password plugin component to be installed. For example: SELECT VALIDATE_PAS... 2024-12-18, 2699🔥, 0💬

Listing All User Accounts in MySQL
How To List All Existing User Accounts in MySQL? MySQL stores all existing user accounts in a table called "mysql.user". If you want see all user accounts, you can use the "SELECT" command as shown in the tutorial exercise below: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf mysql mysql&am... 2017-12-13, 2696🔥, 0💬

Rename an Existing User Account in MySQL
How To Rename an Existing User Account Name in MySQL? If you want to change the name of an existing user account, you can use the "RENAME USER oldName TO newName" command. The tutorial exercise below shows you how to do this: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf mysql mysql&gt... 2017-12-13, 2691🔥, 0💬

Entering Numeric Values as HEX Numbers in MySQL
How To Enter Numeric Values as HEX Numbers in MySQL? If you want to enter numeric values as HEX numbers, you can quote HEX numbers with single quotes and a prefix of (X), or just prefix HEX numbers with (0x). A HEX number string will be automatically converted into a numeric value, if the expression... 2018-03-31, 2689🔥, 0💬

What Is Foreign Key in MySQL
What Is Foreign Key in MySQL? A foreign key is a single column or multiple columns defined to have values that can be mapped to a primary key in another table.   ⇒ What Is Index in MySQL ⇐ What Is Primary key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2683🔥, 0💬

Commit the Current Transaction in MySQL
How To Commit the Current Transaction in MySQL? 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 command. It will make all the database changes made in the current transaction become pe... 2016-10-17, 2682🔥, 0💬

Entering Boolean Values in MySQL
How To Enter Boolean Values in SQL Statements in MySQL? If you want to enter Boolean values in SQL statements, you use (TRUE), (FALSE), (true), or (false). Here are some good examples: SELECT TRUE, true, FALSE, false FROM DUAL; +------+------+-------+------- +| TRUE | TRUE | FALSE | FALSE | +------+... 2018-03-31, 2681🔥, 0💬

JSON_SCHEMA_VALID() - JSON Schema Validation
How to validate a JSON value against a JSON schema using the JSON_SCHEMA_VALID() function? JSON_SCHEMA_VALID(schema, json) is a MySQL built-in function that validates a JSON value against a given JSON schema. For example: SET @schema = '{ "id": "http://json-schema.org/geo", "$schema": "http://json-s... 2024-11-23, 2680🔥, 0💬

Converting Dates to Character Strings in MySQL
How To Convert Dates to Character Strings in MySQL? You can convert dates to character strings using the DATE_FORMAT(date, format) function. MySQL supports the following basic formatting codes: %a Abbreviated weekday name (Sun..Sat) %b Abbreviated month name (Jan..Dec) %c Month, numeric (0..12) %D D... 2017-12-26, 2680🔥, 0💬

Merge Outputs from Two Queries in MySQL
How To Use UNION to Merge Outputs from Two Queries Together in MySQL? If you have two queries that returns the same row fields, you can merge their outputs together with the UNION operator. The following tutorial exercise shows you how to return all links that were created since year 2006 plus the o... 2017-12-21, 2676🔥, 0💬

Query with a Left Outer Join in MySQL
How To Write a Query with a Left Outer Join in MySQL? If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two tables: fyi_links and fyi_rates. The join condition ... 2017-09-28, 2673🔥, 0💬

Entering Microseconds in SQL Statements in MySQL
How To Enter Microseconds in SQL Statements in MySQL? If you want to enter microseconds in a SQL statements, you can enter them right after the time string as a 6-digit number delimited with '.'. '0' will be padded to right if not enough digits. Here are some good examples: SELECT TIME('1997/01/31 0... 2017-12-26, 2671🔥, 0💬

Types of Table Joins in MySQL
How To Join Two Tables in a Single Query in MySQL? 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 fir... 2017-12-31, 2668🔥, 0💬

Retrieving Execution Error Message in MySQL
How To Get MySQL Statement Execution Errors in MySQL? When you execute a MySQL statement with mysql_query(), and the statement failed, mysql_query() will return the Boolean value FALSE. This is good enough to tell that there is something wrong with that statement. But if you want to know more about ... 2017-10-23, 2659🔥, 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, 2657🔥, 0💬

Start a New Transaction Explicitly in MySQL
How To Start a New Transaction Explicitly in MySQL? If you are confused on the implicit new transaction rules, you can always start a new transaction with the "START TRANSACTION" command to start a new transaction explicitly. "START TRANSACTION" command works in both "Autocommit On" and "Autocommit ... 2016-10-17, 2656🔥, 0💬

Converting Character Strings to Dates in MySQL
How To Convert Character Strings to Dates in MySQL? If you have a character string that represents a date, and you want to convert it into a date value, you can use the STR_TO_DATE(string, format) function. STR_TO_DATE() shares the same formatting codes with DATE_FORMAT() function. The tutorial exer... 2017-12-26, 2655🔥, 0💬

Data Removed in MEMORY Tables in MySQL
What Happens to MEMORY Tables When MySQL Server Is Stopped in MySQL? If you have data rows stored in a table with the MEMORY storage engine, and the MySQL server has been shut down by the DBA, all data rows will be removed. But the table structure will remain in the server. The tutorial exercise bel... 2017-08-08, 2655🔥, 0💬

Shutdown MySQL Server Properly in MySQL
How To Properly Shutdown MySQL Server Daemon mysqld in MySQL? The proper way to shutdown your MySQL server is to the use "mysqladmin shutdown" command. Other ways to shutdown your server include: Enter "mysqladmin -u root -ppassowrd shutdown" command with options in a command window. Use Windows Tas... 2017-12-04, 2652🔥, 0💬

Using Subqueries with the EXISTS Operator in MySQL
How To Use Subqueries with the EXISTS Operator in MySQL? A subquery can be used with the EXISTS operator as "EXISTS (subquery)", which returns true if the subquery returns one or more rows. The following statement is a good example of "EXISTS (subquery)". It returns rows from fyi_links table that th... 2017-09-17, 2652🔥, 0💬

Giving User Read-only Access in MySQL
How To Give a User Read-Only Access to a Database in MySQL? If you want give a user read-only access to a database, you can grant to him/her only the "SELECT" privilege, so that he/she can not run any DDL statements, and any INSERT, UPDATE, or DELETE statements. The tutorial exercise gives you a goo... 2017-08-21, 2650🔥, 0💬

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General MySQL Oracle SQL Server