SQL Server 2016 introduced STRING_ESCAPE() to escape the characters like single quotes, double quotes, forward slashes.

SQL Server 2016: Introduced JSON support, to store and retrieve JSON document

Please check the below examples:

Example without STRING_ESCAPE:
Check the below example where I added single quotes, double quotes, forward slashes in the JSON string which is incorrect and IsJSON is also false.

DECLARE @str VARCHAR(800) = 'Anvesh''s blog is "dbrnd.com" which is running from 2015/05/01'
DECLARE @json VARCHAR(800) = '[{"Name":"Anvesh","Gender":"Male","About":"'+@str+'"}]'

SELECT @json as Json

Result:

Json
-------------------------------------------------------------------------------------------------------------
[{"Name":"Anvesh","Gender":"Male","About":"Anvesh's blog is "dbrnd.com" which is running from 2015/05/01"}]

Check IsJSON:

SELECT ISJSON(@json) IsJson

Result:

IsJson
-----------
0

Example with STRING_ESCAPE:
In the below example, check the result of STRING_ESCAPE() and IsJSON is also true.

DECLARE @str VARCHAR(800) = 'Anvesh''s blog is "dbrnd.com" which is running from 2015/05/01'
DECLARE @json VARCHAR(800) = '[{"Name":"Anvesh","Gender":"Male","About":"'+STRING_ESCAPE(@str, 'JSON')+'"}]'

Result:

SELECT @json as Json
Json
-----------------------------------------------------------------------------------------------------------------
[{"Name":"Anvesh","Gender":"Male","About":"Anvesh's blog is \"dbrnd.com\" which is running from 2015\/05\/01"}]

Check IsJSON:

SELECT ISJSON(@json) IsJson

Result:

IsJson
-----------
1

The single quote and apostrophe (s) are commonly used with any text data.
To escape or ignore the single quote is a standard requirement for all database developers.

In this post, I am sharing solution for PostgreSQL Database Server.

PostgreSQL has two options to escape single quote.
You can replace single quote to double single quote like (”) and the other is you can use (E’\’) to escape single quote.

First, Create a sample table:

CREATE TABLE tbl_SingleQuoted
(	
    ID INTEGER
    ,TextData TEXT
);

Insert some sample data with single quote using both (”) and (\’):

INSERT INTO tbl_SingleQuoted 
VALUES 
(1,E'Anvesh\'s dbrnd.com')
,(2,E'Database\'s Properties')
,(3,'The dbrnd Blog''s Reviews');

To SELECT all data which has ( ‘s ):

SELECT *
FROM tbl_SingleQuoted 
WHERE TextData LIKE E'%\'s%';

The Result:

id |         textdata
----+--------------------------
  1 | Anvesh's dbrnd.com
  2 | Database's Properties
  3 | The dbrnd Blog's Reviews

Actually, The funda of $$ – double dollar is very simple, but Postgres new comers have always doubted about it.

When you are writing a PL/pgSQL function, the body of the function has to pass in the form of a string literal.

For example:

Create a sample table:

CREATE TABLE tbl_Students 
(StudID INT, StudName CHARACTER VARYING);

Create a function without $$ – double dollar:

CREATE OR REPLACE FUNCTION fn_TestDelimiter()
RETURNS BOOLEAN AS
'
BEGIN  
	INSERT INTO tbl_Students VALUES (1,''Anvesh'');
	RETURN TRUE; 
END;
'
LANGUAGE plpgsql

We can create a function using single quote and We do not require $$ – double dollar in above example.
But we should not do this, because It is not suggestible to write your function code in single quotes.

When you create your function using single quote, you have to escape all internal single quote in the body.

$$ – Double Dollar:

It is nothing, but just a substitute of a single quote. Using $$ – Double Dollar we can avoid all types of quoting issues.
We can also put token between $$ Double Dollar like: $rnd$ which makes it unique.

For Example:
Create a function with $$ – double dollar:

CREATE OR REPLACE FUNCTION fn_TestDelimiter()
RETURNS BOOLEAN AS
$$
BEGIN  
	INSERT INTO tbl_Students VALUES (1,'Anvesh');
	RETURN TRUE; 
END;
$$
LANGUAGE plpgsql

The single quote and apostrophe (s) are commonly used with any kind of text data.

To escape or ignore the single quote is a common requirement for all database developers.
In this post, I am sharing solution for MySQL Database Server.

MySQL Server has actually two options to escape single quote. You can replace single quote to double single quote like (”) and the other is you can use (\’) to escape single quote.

First, Create a sample table:

CREATE TABLE tbl_SingleQuoted
(	
    ID INTEGER
    ,TextData TEXT
);

Insert some sample data with single quote using both (”) and (\’):

INSERT INTO tbl_SingleQuoted 
VALUES 
(1,'Anvesh\'s dbrnd.com')
,(2,'Database\'s Properties')
,(3,'The dbrnd Blog''s Reviews');

To SELECT all data which has ( ‘s ):

SELECT *
FROM tbl_SingleQuoted 
WHERE TextData LIKE '%\'s%';

The Result: