one sql command in php's script

$sql = 'INSERT INTO joke SET joketext="' . $joketext . '", jokedate="today's date"';

i don't understand this part

joketext="' . $joketext . '",

in it,why it use the single quote and the concatenation . i feel those are a surplus, use this

joketext="$joketext ",

is ok, but when i test it ,it's show an error,any tips would be appreciated.

runeveryday wrote:
is ok, but when i test it ,it's show an error,any tips would be appreciated.

Then obviously it's not okay....

PHP needs string literals to be quoted.

PHP sends that string to the DBMS.

The DBMS needs string literals to be quoted.

Hence, two sets of quotes.

What most people use is

$sql = "INSERT INTO .......etc.....";

So, I understand you. It looks unusual and also not how I and most would do it.
It is certainly possible to do so, but not what most do.

Another thing I really put a big questionmark for is this:

jokedate="today's date"

"today's date" .... I can not imagine any database accepts this for to define the date of today.

So, in my examples here I will just use "today",
as "today's date" have a disturbing single quote inside of it.

This is how most would do it. And me too.
It is simple and would work 100%

$sql = "INSERT INTO joke SET joketext='$joketext', jokedate='today'";

Here is my variant of the example you ask about.
This splits the $sql into two strings
and put the $joketext variable in the middle between:

$sql = "INSERT INTO joke SET joketext='" . $joketext . "', jokedate='today'";

Here is the example you refer to again.
Also splits the query string into two and put the variable in between:

$sql = 'INSERT INTO joke SET joketext="' . $joketext . '", jokedate="today"';