TCL commands

TCL COMMANDS:

1. COMMIT:

Commits a Transaction. The COMMIT command saves all the transactions to the database since the last COMMIT or ROLLBACK command.

Syntax: COMMIT;

Example:

DELETE FROM Student WHERE AGE = 21; COMMIT:

2. ROLLBACK:

If any error occurs with any of the SQL-grouped statements, all changes need to be aborted. The process of reversing changes is called rollback

Syntax: ROLLBACK;

Example:

DELETE FROM Student WHERE AGE = 21; ROLLBACK;

↑

DML commands

DML COMMANDS:

1. INSERT:

SQL INSERT statement is a SQL query. It is used to insert a single or a multiple records in a table.

Syntax:

INSERT INTO table_name

VALUES (value1, value2, value3 .....);

Example:

INSERT INTO STUDENTS (ROLL_NO, NAME, AGE, CITY) VALUES (1,naresh, 21, hyd)

3. ALTER:

The ALTER TABLE statement in Structured Query Language allows you to add, modify, and delete columns of an existing table.

Syntax:

ALTER table_name

ADD column_name datatype;

Example:

ALTER TABLE EMPLOYEE ADD Email varchar (255);

4. DROP:

The DROP TABLE statement is used to drop an existing table in a database. This command deletes both the structure & Records Stored in the table.

Syntax:

DROP TABLE table_name;

Example:

DROP TABLE Employee

DDL commands

DDL COMMANDS:

• DTM (Data Defined Languages) used to change the structure of the table Like creating the table, altering the table & Deleting the table.

All the commands in the DDL are auto Committed that means it permanently save all the changes in the database.

1. CREATE :

This command is used to create a new database or table.

Syntax:

CREATE TABLE table_name( columnl datatype, column2 datatype, column3 datatype,

Example:

CREATE TABLE Employee

EmployeelD int; FirstName varchar(255), LastName varchar(255), AddressLine varchar(255), City varchar(255)

);

2. UPDATE:

The UPDATE statement is used to modify the existing records in a table.

Syntax:

UPDATE table_name

SET colomn1 = value1, colomn2 = value2,..... WHARE CustomerID = 101;

Example:

UPDATE Customers

SET ContactName = 'naresh', City = 'hyd' WHERE CustomerID = 101;

3. DELETE :

The DELETE statement is used to delete the existing records in a table.

Syntax:

DELETE FROM table_name[WHERE condition];

Example:

DELETE Customers WHERE CuntomerName = "naresh";

4. TRUNCATE:

A truncate SQL statement is used to remove all rows (complete data) from a table. It is similar to the DELETE statement with no WHERE clause.

Syntax:

TRUNCATE TABLE table_name;

Example:

TRUNCATE TABLE Employee;

what is SQL ?

sql is stand for structured query language.

• This database language is mainly designed for maintaining the data in relational database management systems.

• sql is standard language for accessing and manipulating database

This site can't be reached error

Solution 1:

1. open cmd as admin
2. cd C:\Program Files (x86)\IIS Express
3. IisExpressAdminCmd.exe setupsslUrl -url:https://localhost:portnumber/ -UseSelfSigned

Solution 2:

exception has been thrown by the target of an invocation in c#

 changes dll version or upgrade dll .. change old dll library to new dll library

...\packages\EntityFramework.6.2.0\lib\net45\EntityFramework.dll

Database from SINGLE USER mode to MULTI USER

 USE master;

GO

ALTER DATABASE MyDb2022

SET SINGLE_USER

WITH ROLLBACK IMMEDIATE;

GO

ALTER DATABASE MyDb2022

SET READ_ONLY;

GO

How to insert a string value with an apostrophe (single quote) in a column

 INSERT INTO testtable VALUES (1,'Naresh C'houlla')

Msg 102, Level 15, State 1, Line 1
Incorrect syntax near ‘houlla’.
Msg 105, Level 15, State 1, Line 1
Unclosed quotation mark after the character string ‘)

 INSERT INTO testtable VALUES (1,'Naresh C''houlla')

Windows Malicious Software Removal Tool and record screen

Windows Malicious Software Removal Tool without software installation.. 

type mrt in the Windows search bar or Windows + R and type mrt.. 

and record - windows + alt +r or windows + g 

Cannot create/shadow copy 'dll' when that file already exists.

 updating your web.config with the following entry:

<configuration>

   <system.web>

      <hostingEnvironment shadowCopyBinAssemblies="false" />

   </system.web>

</configuration>