In MySQL Workbench I want to replace all instances of newlines with the explicit string "\\n" in my entire database, except where the string already exists. How would I form the query? Thanks.
[edit]
It just occurred to me that it might be easier to dump the database and use Notepad++ to replace the strings. But I was hoping there were a way to do this from within MySQL Workbench itself.
You will need to do this for each table and each column that you want to do the replacement. For example:
update table set column = REPLACE(column,'\n','\\n')
Related
I am migrating a database from PostgresSql to MySql.
We were saving files in the database as PostgreSQL bytea columns. I wrote a script to export the bytea data and then insert the data into a new MySql database as a blob. The data is inserting into Mysql fine, but it is not working at the application level. However, the application should not care, as the data is exactly the same. I am not sure what is wrong, but I feel like it is some difference between MySql vs. PostgreSQL. Any help would be greatly appreciated.
This could really be a number of issues, but I can provide some tips in regards to converting binary data between sql vendors.
The first thing you need to be aware of is that each sql database vendor uses different escape characters. I suspect that your binary data export is using hex and you most likely have unwanted escape characters when you import to your new database.
I recently had to do this. The exported binary data was in hex and vendor specific escape characters were included.
In your new database, check if the text value of the binary data starts with an 'x' or unusual encoding. If it does you need to get rid of this. Since you already have the data inserting properly, to test, you can just write an sql script to remove any unwanted vendor specific escape characters from each imported binary data record in your new database. Finally, you may need to unhex each each new record.
So, something like this worked for me:
UPDATE my_example_table
SET my_blob_column = UNHEX(SUBSTRING(my_blob_column, 2, CHAR_LENGTH(my_blob_column)))
Note: The 2 in the SUBSTRING function is because the export script
was using hex and prepending '\x' as a vendor specific escape character.
I am not sure that will work for you, but it maybe worth a try.
I want to search for http://example.com and replace with https://example.com.
I know I can target a specific table and column with this approach:
UPDATE table_name SET post_content = REPLACE(column_name, 'http://example.com', 'https://example.com');
But how do I run a query which targets all tables/columns: the entire database?
Do a DB dump and open it as a text file. Find and replace. Save and then re-import.
As far as I know, I don't think you can use REPLACE on all tables in one query.
There a two ways to do it. The first is to create SQL UPDATE via the information_schema and execute it as prepared statement. this is much work.
you must look at each column if you can do a replace, so you must ignore INTS and ENUMs etc.
The second way is not a real SQL change, but it works: Generate a full SQL-Dump from your database and make the changes in this file via editor or via commandline with AWK or SED. After this you can import the changed file
So I don't want this thread to be marked as spam, as a previous thread was on this topic was, so I will explain what I have done so far and my issue is and ask if there are any solutions.
I have a MySQL database on my laptop that I need to migrate to DB2 on iSeries. I'm using a tool, I won't say which one because of the spam issue, which allows me to "copy" a table in my MySQL database and "paste" it into my DB2 database.
The issue that I'm having is because the table names and column names contain spaces in the MySQL db, the tool is failing on the paste. I confirmed this by altering one table by replacing the spaces with underscores and the copy worked perfectly. I have over a hundred tables I need to copy over and don't want to have to manually edit every table and column name.
Is there a way to globally replace spaces with underscores in MySQL table names and columns?
Any other ideas? I'm also researching a way to force the query the tool creates to enclose the object names in quotes, but have had no luck so far.
Thanks for any help and suggestions you can provide.
Since Stack Overflow is about helping to solve programming problems, I'm going to ignore the issue of deficiencies in the chosen tool and propose a programming solution to the larger problem - DB2 does not allow spaces in table and column names. You did ask for any suggestions...
Write code that reads the MySQL catalog tables. In DB2 they'd be SYSTABLES, SYSVIEWS, SYSINDEXES, SYSCOLUMNS, etc. Read SYSTABLES and use that as the 'primary' source for the rest of the code. Check the table name; if it has an embedded space, replace it with an underscore. Use SYSCOLUMNS to generate a CREATE TABLE statement that will create the new table (in a new MySQL database?) - also performing space to underscore replacement. After issuing the CREATE TABLE, generate an SQL statement that will INSERT INTO the new table the columns from the old table; again doing the space to underscore substitutions. Once the new table is populated, generate SQL statements to CREATE VIEW, CREATE PROCEDURE, CREATE FUNCTION, etc.
The general idea is that you will completely re-create your MySQL database with table, view and column names that are immediately compatible with DB2 for i so that your tool can do it's thing.
Of course, if you go to that much trouble it'll probably be just as easy to directly CREATE TABLE, etc on the IBM i side rather than go through an intermediate tool that isn't quite what you need.
I imported data from csv files into a MySQL database, but made the mistake of not
removing the trailing spaces in the csv columns. So the spaces are seen as '?' at
the end of some values in the database (of type Varchar). I want to get rid of these.
Can I somehow delete all these ?s in the database in one go? I know of the replace
command, but I think that works on a single column of a singe table at a time, which will
be very time consuming for me. Could anyone please suggest something better? Thanks!
You can use the trim function
UPDATE table SET column = TRIM(TRAILING '?' FROM column)
I have a text file to be imported in a MySQL table. The columns of the files are comma delimited. I set up an appropriate table and I used the command:
load data LOCAL INFILE 'myfile.txt' into table mytable FIELDS TERMINATED BY ‘,’;
The problem is, there are several spaces in the text file, before and after the data on each column, and it seems that the spaces are all imported in the tables (and that is not what I want). Is there a way to load the file without the empty spaces (other than processing each row of the text file before importing in MySQL)?
As far as I understand, there's no way to do this during the actual load of the data file dynamically (I've looked, as well).
It seems the best way to handle this is to either use the SET clause with the TRIM
function
("SET column2 = TRIM(column2)")
or run an update on the string columns after loading, using the TRIM() function.
You can also create a stored procedure using prepared statements to run the TRIM function on all columns in a specified table, immediately after loading it.
You would essentially pass in the table name as a variable, and the sp would use the information_schema database to determine which columns to upload.
If you can use .NET, CSVReader is a great option(http://www.codeproject.com/KB/database/CsvReader.aspx). You can read data from a CSV and specify delimiter, trimming options, etc. In your case, you could choose to trim left and right spaces from each value. You can then either save the result to a new text file and import it into the database, or loop through the CsvReader object and insert each row into the database directly. The performance of CsvReader is impressive. Hope this helps.