Mysql:Trim all fields in database

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耶瑟儿~
耶瑟儿~ 2021-02-12 08:37
UPDATE mytable SET mycolumn= LTRIM(RTRIM(mycolumn));

works fine on trimming columns removing trailer spaces, but how can i adjust it to trim all column

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  • 2021-02-12 08:52

    If there are not too many columns, you could just
    directly UPDATE each by your_column_name, via the TRIM() function:

    UPDATE mytable SET 
    mycolumn1 = TRIM(mycolumn1), 
    mycolumn2 = TRIM(mycolumn2),
    mycolumn3 = TRIM(mycolumn3),
    mycolumn4 = TRIM(mycolumn4)
    

    Otherwise, ZweiStein's answer above for a single table,
    or Izhar Aazmi's answer for an entire database seem the way to go.

    Hiram's answer to another SO Post includes a check to only TRIM VARCHAR fields: excellent feature!

    Or, if using T-SQL, or others which do not support TRIM, use the LTRIM(RTRIM(...)) trick,
    suggested by Jim Rubenstein and Denis de Bernardy above.

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  • 2021-02-12 08:53
    UPDATE mytable SET 
    mycolumn = LTRIM(RTRIM(mycolumn)), 
    mycolumn2 = LTRIM(RTRIM(mycolumn2)) 
    

    and so on, and so forth.

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  • 2021-02-12 09:05

    Some years late, but might help others: This code trims all fields of a the table "your_table". Could be expanded to work on the whole database in the same way....

    SET SESSION group_concat_max_len = 1000000;
    select concat('update your_table set ',group_concat(concat('`',COLUMN_NAME, '` = trim(`',COLUMN_NAME,'`)')),';')
       FROM INFORMATION_SCHEMA.COLUMNS
        WHERE table_name = 'your_table'
        into @trimcmd;
    
    prepare s1 from @trimcmd;
    execute s1;
    DEALLOCATE PREPARE s1;
    
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  • 2021-02-12 09:07

    Since the question asks for the whole database, here is the script that generates the required SQL. I skip the auto execute, execute it as you like.

    -- Set your database name here
    SET @my_database:='YOUR_DB_NAME';
    
    SET SESSION group_concat_max_len = 1000000;
    
    SELECT 
        CONCAT('UPDATE `', @my_database, '`.`', TABLE_NAME, 
                '` SET ', GROUP_CONCAT(
                    CONCAT('`', COLUMN_NAME, '` = TRIM(`', COLUMN_NAME, '`)')
                    ORDER BY ORDINAL_POSITION ASC),
                ';') AS `query`
    FROM
        INFORMATION_SCHEMA.COLUMNS
    WHERE
        TABLE_SCHEMA = @my_database
    GROUP BY TABLE_NAME
    ORDER BY TABLE_NAME ASC;
    

    @ZweiStein Thanks.

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  • I was actually looking for something similar for a legacy table that's constantly updated by an outside source when I came across this question. I realize the OP was looking for a purely SQL(MySQL) answer, but in case you use Rails, you might find this tidbit that I came up with helpful:

    MyModel.update_all(MyModel.columns.map(&:name).map{|x| "#{x} = TRIM(#{x})"}.join(', '))
    

    You can also wrap it into a class method in your model

    class MyModel < ActiveRecord::Base
      def self.trim_all
       update_all(columns.map(&:name).map{|x| "#{x} = TRIM(#{x})"}.join(', '))
     end
    end
    

    Then call it like this

    MyModel.trim_all
    
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  • 2021-02-12 09:09

    You can use PHP for it ( in order to avoid sql errors, better print queries then execute them later ) :

    $dbHost = 'localhost';
    $dbUsername = 'root';
    $dbPassword = '';
    $dbName = 'database';
    $db = new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);
    $db->set_charset("utf8");
    
    $queries = '';
    $query="SELECT * from table";
    $result = $db->query($query);
    $headers = $result->fetch_fields();
    foreach($headers as $header) {
            $col = $header->name;
    
           $queries .= "UPDATE table SET `".$col."` = TRIM(`".$col."`) </br>";
    }
    echo $queries;
    

    ?>

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