In php, how does the json_encode function contain single quotes?

How does {code...} solve this problem? Directly replace single quotes?

  "Test the problem of saving the single quote", "name" => "tom"]; $ str = json_encode ($ arr); print_r ($ str ); // Save $ str to the database. single quotation marks fail. $ SQL = "UPDATE test SET str = '". $ str. "'Where id = 1"; $ db-> query ($ SQL);?>

How can this problem be solved? Directly replace single quotes?

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  "Test the problem of saving the single quote", "name" => "tom"]; $ str = json_encode ($ arr); print_r ($ str ); // Save $ str to the database. single quotation marks fail. $ SQL = "UPDATE test SET str = '". $ str. "'Where id = 1"; $ db-> query ($ SQL);?>

How can this problem be solved? Directly replace single quotes?

Mysqli_real_escape_string ()
PDO: quote
Mysql_real_escape_string

Do not use string concatenation, instead of using PDO and MYSQLi with the Prepared Statement mechanism.

Escape and save