MySQL - 替换列中的字符

Question

Being a self-taught newbie, I created a large problem for myself. Before inserting data in to my database, I've been converting apostrophes (') in a string, to double quotes (""), instead of the required back-slash and apostrophe (\\'), which MySQL actually requires.

Before my table grows more than the 200,000 rows it already is, I thought it was best to rectify this issue immediately. So I did some research and found the SQL REPLACE function, which is great, but I'm now confused.

In ASP, I was doing this:

str = Replace(str,"'","""")

If I look at my database in SQL Workbench, the symbol I converted is now a single quote ("), which has confused me a little. I understand why it changed from double to single, but I don't know which one I'm meant to be changing now.

To go through and rectify my problem using SQL REPLACE, do I now convert single quotes (") to back-slash and apostrophes (\\') or do I convert double quotes ("") to back-slash and apostrophes (\\')?

For example, this:

SQL = " SELECT REPLACE(myColumn,"""","\'") FROM myTable "

or this:

SQL = " SELECT REPLACE(myColumn,""","\'") FROM myTable "

I hope I explained myself well, any suggestions gratefully received as always. Any queries about my question, please comment.

Many thanks

-- UPDATE --

I have tried the following queries but still fail to change the ( " ) in the data:

SELECT REPLACE(caption,'\"','\'') FROM photos WHERE photoID = 3371
SELECT REPLACE(caption,'"','\'') FROM photos WHERE photoID = 3371
SELECT REPLACE(caption,'""','\'') FROM photos WHERE photoID = 3371

Yet if I search:

SELECT COUNT(*) FROM photos WHERE caption LIKE '%"%'

I get 16,150 rows.

-- UPDATE 2 --

Well, I have created a 'workaround'. I managed to convert an entire column pretty quickly writing an ASP script, using this SQL:

SELECT photoID, caption FROM photos WHERE caption LIKE '%""%';

and then in ASP I did:

caption = Replace(caption,"""","\'")

But I would still like to know why I couldn't achieve that with SQL?

Answer 1

Just running the SELECT statement will have no effect on the data. You have to use an UPDATE statement with the REPLACE to make the change occur:

UPDATE photos
   SET caption = REPLACE(caption,'"','\'')

Here is a working sample: http://sqlize.com/7FjtEyeLAh

Answer 2

Replace below characters

~ ! @ # $ % ^ & * ( ) _ +
` - = 
{ } |
[ ] \
: " 
; '

< > ?
, . 

with this SQL

SELECT note as note_original, 

    REPLACE(
        REPLACE(
            REPLACE(
                REPLACE(
                    REPLACE(
                        REPLACE(
                            REPLACE(
                                REPLACE(
                                    REPLACE(
                                        REPLACE(
                                            REPLACE(
                                                REPLACE(
                                                    REPLACE(
                                                        REPLACE(
                                                            REPLACE(
                                                                REPLACE(
                                                                    REPLACE(
                                                                        REPLACE(
                                                                            REPLACE(
                                                                                REPLACE(
                                                                                    REPLACE(
                                                                                        REPLACE(
                                                                                            REPLACE(
                                                                                                REPLACE(
                                                                                                    REPLACE(
                                                                                                        REPLACE(
                                                                    REPLACE(
                                                                        REPLACE(
                                                                            REPLACE(
                                                                                REPLACE(
                                                                                    REPLACE(
                                                                                        REPLACE(
                                                                                            REPLACE(note, '\"', ''),
                                                                                        '.', ''),
                                                                                    '?', ''),
                                                                                '`', ''),
                                                                            '<', ''),
                                                                        '=', ''),
                                                                    '{', ''),
                                                                                                        '}', ''),
                                                                                                    '[', ''),
                                                                                                ']', ''),
                                                                                            '|', ''),
                                                                                        '\'', ''),
                                                                                    ':', ''),
                                                                                ';', ''),
                                                                            '~', ''),
                                                                        '!', ''),
                                                                    '@', ''),
                                                                '#', ''),
                                                            '$', ''),
                                                        '%', ''),
                                                    '^', ''),
                                                '&', ''),
                                            '*', ''),
                                        '_', ''),
                                    '+', ''),
                                ',', ''),
                            '/', ''),
                        '(', ''),
                    ')', ''),
                '-', ''),
            '>', ''),
        ' ', '-'),
    '--', '-') as note_changed FROM invheader

Answer 3

maybe I'd go by this.

 SQL = SELECT REPLACE(myColumn, '""', '\'') FROM myTable

I used singlequotes because that's the one that registers string expressions in MySQL, or so I believe.

Hope that helps.

Answer 4

如果你有“某事”并需要'某事'，请使用replace(col, "\\"", "\\'")和反之。