In-depth explanation of the failure of writing SQL containing English single quotation marks "''"

I have encountered a problem. When testing the editing of information, if the edited content contains a single quote ('), it will fail to be written to the MySQL database. Use the following code to print the error:

if (!this->m_sql_query.prepare(update_string))
{
printf("exec fail—>%s\n", this->m_sql_query.lastError().text().toStdString().c_str());
}
if (!this->m_sql_query.exec())
{
printf("exec fail—>%s\n", this->m_sql_query.lastError().text().toStdString().c_str());
}

The printed result is: exec fail—>syntax error unable to execute statement

Please refer to the following relevant information:

After analysis, it was found that the string in the inserted content was truncated at the single quotes when editing the SQL statement, resulting in a syntax error.

Solution : Replace the characters containing single quotes (') with ('').

SQL uses two single quotes instead of one single quote.

str = str.replace(” '“, ”''“);

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