Extra escaping when backslash in enum value

[iggyvolz]

Steps to reproduce this issue

1. Create/access a table with a backslash in the enum value - CREATE TABLE x (c ENUM('\\foo','\\bar'))
2. Attempt to insert/update a row with a value with a backslash through the data tab

Current behavior

HeidiSQL double-escapes the input, leading to the query INSERT INTO `test`.`x` (`c`) VALUES ('\\\\foo'); and /* SQL Error (1265): Data truncated for column 'c' at row 1 */

Expected behavior

HeidiSQL should generate the query INSERT INTO `test`.`x` (`c`) VALUES ('\\foo');, which is successful when run manually

Possible solution

The enum value is escaped for backslashes twice (or once too many). Possibly similar to #690.

Environment

• HeidiSQL version: Windows, latest nightly
  
• Database system and version: MariaDB 10.4.8
• Operating system: Windows 10 [Version 10.0.18362.418]

[ansgarbecker]

I think the problem is HeidiSQL does not un-escape the two backslashes when parsing the table structure. The real value for an enum('\\foo') is '\foo', not '\\foo', while an INSERT again has to duplicate that single slash: INSERT INTO ... VALUES ('\\foo'). Quite confusing, right? :)