General MySQL Oracle SQL Server

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Entering Numeric Values in MySQL
How To Include Numeric Values in SQL statements in MySQL? If you want to include a numeric value in your SQL statement, you can enter it directly as shown in the following examples: SELECT 255 FROM DUAL; -- An integer 255 SELECT -6.34 FROM DUAL; -- A regular number -6.34 SELECT -32032.6809e+10 FROM ... 2018-03-31, 2924🔥, 0💬

Experiment with Dead Locks in MySQL
How To Experiment Dead Locks in MySQL? If you want to have some experience with dead locks, you can create two windows running two mysql transactions in two sessions at the REPEATABLE READ transaction isolation level. Then run some UPDATE statements as shown in the tutorial exercise below: (session ... 2017-07-21, 2924🔥, 0💬

"SELECT" Statements - Reading the Data In a Table in SQL Server
How to read data in a table with "SELECT" statements in SQL Server? This is the fourth tutorial of a quick lesson on creating database objects with Transact-SQL statements. This lesson shows you how to create a database, create a table in the database, and then access and change the data in the tabl... 2016-12-02, 2923🔥, 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, 2922🔥, 0💬

Types of Execution Flow Control Statements in Oracle
What Are the Execution Control Statements in Oracle? PL/SQL supports three groups of execution control statements: IF Statements - Conditionally executes a block of statements. CASE Statements - Selectively executes a block of statements. LOOP Statements - Repeatedly executes a block of statements. ... 2018-11-17, 2920🔥, 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, 2918🔥, 0💬

Creating Stored Procedures with Parameters in SQL Server
How To Create Stored Procedures with Parameters in SQL Server Transact-SQL? Very often, you need to create a stored procedure with one or more parameters. You only supply values to those parameters at the time of executing the stored procedure. Stored procedures with parameters can be created with t... 2017-01-05, 2917🔥, 0💬

Duplicate Key Error on Primary Key Columns in SQL Server
What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server? If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow dupl... 2016-11-02, 2917🔥, 0💬

Retrieving the Last Sequence ID in MySQL
How To Get the Last ID Assigned by MySQL in MySQL? If you use an ID column with AUTO_INCREMENT attribute, you can use the mysql_insert_id() function to get the last ID value assigned by the MySQL server, as shown in the sample script below: &lt;?php include "mysql_connection.php"; $sql = "INSERT... 2017-09-12, 2916🔥, 0💬

Work with Data Objects Interactively in Oracle
How To Work with Data Objects Interactively in Oracle? You can work with data objects through SQL statements in statement area. If you want to work with data objects interactively, you should use the object browser. The following tutorial steps help you to browse data objects: Click the Connetions t... 2018-10-08, 2915🔥, 0💬

Assign a Table Row to RECORD Variable in Oracle
How To Assign a Table Row to a RECORD Variable in Oracle? If you have a table, and want to assign a data row of that table to a RECORD variable, you need to define this RECORD variable to match the table column structure, then use the SELECT ... INTO statement to assign a data row that RECORD variab... 2018-08-14, 2915🔥, 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, 2914🔥, 0💬

Using SELECT Statements with Joins and Subqueries in SQL Server
Where to find answers to frequently asked questions on Using SELECT Statements with Joins and Subqueries in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using SELECT Statements with Joins and Subqueries in SQL Server. Clear answers ... 2016-10-30, 2913🔥, 0💬

PHP ODBC - odbc_fetch_array() - Looping through Returning Rows
PHP ODBC - How To Loop through Returning Rows? The best way to query tables and loop through returning rows is to run a SELECT statement with the odbc_exec() function, catch the returning object as a result set, and loop through the result with odbc_fetch_array() function in a while loop as shown in... 2024-05-29, 2912🔥, 0💬

Loop through the Implicit Cursor in Oracle
How To Loop through Data Rows in the Implicit Curosr in Oracle? You use the FOR ... IN ... LOOP statement to loop through data rows in the implicit cursor as the following syntax: FOR row IN dml_statement LOOP (statement block with row.field) END LOOP; Here "row" is a local RECORD type variable with... 2018-07-22, 2911🔥, 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, 2911🔥, 0💬

Expressions with NULL Values in MySQL
What Happens If NULL Values Are Involved in Expressions in MySQL? If NULL values are used in expressions, the resulting values will be NULL values. In other words: Arithmetic expressions with NULL values result NULL values. Comparison expressions with NULL values result NULL values. Logical expressi... 2018-03-28, 2910🔥, 0💬

Converting Numeric Data Types by Assignment Operations in SQL Server
How To Convert Numeric Expression Data Types by Assignment Operations in SQL Server Transact-SQL? An assignment operation is used to assign an expression to a variable, a column, or a parameter. If the data type of the expression does not match the data type of the receiving variable, column, or par... 2017-03-27, 2909🔥, 0💬

Updating Values in a Table in MySQL
How To Update Values in a Table in MySQL? If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: mysql&gt; UPDATE fyi_links SET counts = 999, notes = 'Good.' WHERE id = 101; Query OK, 1 row affec... 2018-01-13, 2908🔥, 0💬

Getting Month and Weekday Names from DATATIME Values in SQL Server
How To Get Month and Weekday Names from DATETIME Values in SQL Server Transact-SQL? In DATETIME values, the month part and weekday part have names. You can use the DATENAME() function to get the month name and weekday name from a DATETIME value in the following format: DATENAME(datepart, date) retur... 2017-02-14, 2907🔥, 0💬

PHP MSSQL - Query Multiple Tables Jointly
PHP MSSQL - How To Query Multiple Tables Jointly? If you want to query information stored in multiple tables, you can use the SELECT statement with a WHERE condition to make an inner join. Assuming that you have 3 tables in a forum system: "users" for user profile, "forums" for forums information, a... 2024-02-09, 2906🔥, 0💬

Overflow Errors on Converting Big Values to Integers in SQL Server
What Happens When Converting Big Values to Integers in SQL Server Transact-SQL? If you are converting a numeric expression to an integer data type and the value is too big for integer storage size, you will get an arithmetic overflow error as shown in the following examples: -- Overflow error on imp... 2017-03-22, 2906🔥, 0💬

What Are Group Functions in MySQL
What Are Group Functions in MySQL? Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each row of the group. MAX(exp) - Returns the maximum ... 2018-01-06, 2905🔥, 0💬

Server Daemon mysqld Administration in MySQL
Where to find answers to frequently asked questions on Server Daemon mysqld Administration in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Server Daemon mysqld Administration in MySQL. Clear answers are provided with tutorial exercises o... 2017-12-09, 2904🔥, 0💬

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General MySQL Oracle SQL Server