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How Data Locks Are Respected in Oracle
How Data Locks Are Respected in Oracle? Here are the rules on how data locks are respected: All statements ignore data locks owned its own transaction. SELECT query statements ignores data locks owned by any transactions. INSERT, UPDATE, and DELETE statements in a READ COMMITTED transaction will wai...
2019-08-08, 585👍, 0💬

Primary Key - Default Indexes of Tables in SQL Server
Is the PRIMARY KEY Column of a Table an Index in SQL Server? If you define a primary key on a table, an index for the primary key column will be created by default. The tutorial exercise below shows you the index created as part of the primary key column of "fyi_links": USE FyiCenterData; GO -- Drop...
2016-11-13, 585👍, 0💬

What Is a SELECT Query Statement in SQL Server
What Is a SELECT Query Statement in SQL Server? The SELECT statement is also called the query statement. It is the most frequently used SQL statement in any database application. SELECT statements allows you to retrieve data from one or more tables or views, with different selection criteria, groupi...
2016-10-26, 585👍, 0💬

Selecting All Columns of All Rows in MySQL
How To Select All Columns of All Rows from a Table in MySQL? The simplest query statement is the one that selects all columns of all rows from a single table: "SELECT * FROM tableName;". The (*) in the SELECT clause tells the query to return all columns. The missing WHERE clause tells the query to r...
2017-11-05, 583👍, 0💬

"CREATE TABLE" Statement - Creating New Tables in SQL Server
How to create new table with "CREATE TABLE" statements in SQL Server? This is the second 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 ta...
2016-12-02, 583👍, 0💬

Using Group Functions in the SELECT Clause in SQL Server
How To Use Group Functions in the SELECT Clause in SQL Server? If group functions are used in the SELECT clause, all rows that meet the criteria defined in the WHERE clause will be treated as a single group. The group functions will be apply all rows in that group as a whole. The final output of the...
2016-10-25, 583👍, 0💬

"GROUP BY" - Dividing Query Output into Multiple Groups in SQL Server
How To Divide Query Output into Multiple Groups with the GROUP BY Clause in SQL Server? Sometimes, you want to divide the query output into multiple groups, and apply group functions on each individual groups. Dividing query output into multiple groups can be done with the GROUP BY clause. Here is t...
2016-10-25, 583👍, 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, 582👍, 0💬

Create a Test Table with Test Data in MySQL
How To Create a Testing Table with Test Data in MySQL? If you want to follow the tutorial exercises presented in this collection, you need to create a testing table and insert some test data, as shown in the following sample script: mysql&gt; CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url V...
2017-11-05, 582👍, 0💬

Subtracting a DATETIME Value from Another DATETIME Value in SQL Server
Can a DATETIME Value Be Subtracted from Another DATETIME Value in SQL Server Transact-SQL? Can a datetime value be subtracted from another datetime value? The answer is yes. The subtract operation can be performed by the subtract operator (-) as: datetime1 - datetime2: Returning a DATETIME value cal...
2017-02-20, 582👍, 0💬

Joining Two Tables in a Single Query in SQL Server
How To Join Two Tables in a Single Query in SQL Server? 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 th...
2016-10-30, 582👍, 0💬

What Is a Database in SQL Server
What is a database in SQL Server? A database is a logical container that contains a set of related database objects: Tables - Storages of structured data. Views - Queries to present data from tables. Indexes - Sorting indexes to speed up searches. Stored Procedures - Predefined SQL program units. Us...
2016-11-24, 581👍, 0💬

Build Data Dictionary View in Oracle
How To Build Data Dictionary View of an New Database in Oracle? This is Step 9. The Oracle Administrator Guide suggests to run two SQL scripts provided by Oracle as shown bellow: SQL&gt; @/u01/oracle/rdbms/admin/catal og.sqlSQL&gt; @/u01/oracle/rdbms/admin/catpr oc.sql  ⇒Creating New Databas...
2019-03-27, 579👍, 0💬

Assign Data from a Deleted Row to Variables in Oracle
How To Assign Data of the Deleted Row to Variables in Oracle? If a DELETE statement is deleting a single row, you can assign column values of the deleted row to variables by using the RETURNING clause, which an extension of DELETE statements for PL/SQL. The tutorial script shows you how to do this: ...
2018-09-13, 579👍, 0💬

Incrementing a Date by 1 in MySQL
How To Increment Dates by 1 in MySQL? If you have a date, and you want to increment it by 1 day, you can use the DATE_ADD(date, INTERVAL 1 DAY) function. You can also use the date interval add operation as "date + INTERVAL 1 DAY". The tutorial exercise below gives you some good examples: SELECT DATE...
2017-12-26, 579👍, 0💬

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, 575👍, 0💬

Running MySQL Server on a Specific Port in MySQL
How To Run MySQL Server on a Different Port in MySQL? By default, MySQL will listen at port number 3306 for any client connections. But you can change this by starting the server with "--port=portNumber" option. The tutorial exercise shows you how to start the server to listen to a different port nu...
2017-11-29, 575👍, 0💬

OFFLINE - Taking a database offline in SQL Server
How to set a database state to OFFLINE in SQL Server? If you want to move database physical files, you should take the database offline by using the "ALTER DATABASE" statement with the following syntax: ALTER DATABASE database_name SET OFFLINE The following tutorial example will bring "FyiCenterComD...
2016-11-20, 575👍, 0💬

"CREATE LOGIN" Statements - Creating a Login in SQL Server
How to create a login to access the database engine using "CREATE LOGIN" statements in SQL Server? This is the first 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 crea...
2016-12-02, 574👍, 0💬

Categories of Functions Based on Return Modes in SQL Server
How Many Categories of Functions based Their Return Modes in SQL Server Transact-SQL? SQL Server supports 2 categories of user defined functions based on their return modes: 1. Scalar-valued Functions - A function that returns a single value. Scalar-valued functions can be used in scalar expressions...
2016-12-18, 573👍, 0💬

Creating a New Table in a Given Schema in SQL Server
How To Create a New Table in a Given Schema in SQL Server? When you create a new table, you can specify in which schema you want this table to be located by prefixing the table name with the schema name. In the tutorial example below, a new table "test" is created in schema "fyi": USE FyiCenterData;...
2016-10-22, 573👍, 0💬

Deleting Data from a View in SQL Server
Can You Delete Data from a View in SQL Server? Can you delete data in a view? The answer is no. But if the question is "Can you delete data from the underlying table through view?" The answer is then yes. SQL Server will allow you to delete data from the underlying table through a view. The tutorial...
2016-11-03, 572👍, 0💬

Transferring Tables from One Schema to Another in SQL Server
How To Transfer an Existing Table from One Schema to Another Schema in SQL Server? If you want to move an existing table from one schema to another schema, you can use the "ALTER SCHEMA ... TRANSFER ..." statement as shown in the tutorial exercise below: -- Login with "sa" USE FyiCenterData; GO -- C...
2016-10-22, 571👍, 0💬

Renaming Database Names in SQL Server
How to rename databases in SQL Server? If don't like the name of a database, you can change it by using the "ALTER DATABASE" statement with the following syntax: ALTER DATABASE database_name MODIFY NAME = new_database_name The tutorial example below shows you how change the database name from "FyiCe...
2016-11-24, 570👍, 0💬

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