How to concatenate MySQL columns without listing all columns?

How to Concatenate MySQL Columns Effectively

Concatenating all columns in MySQL using the * keyword is not feasible. Instead, you need to explicitly list all columns you wish to combine.

Explicit Column Concatenation

To achieve this, use the CONCAT function:

SELECT CONCAT(col1, col2, col3, ....)
FROM yourtable

Alternatively, you can utilize CONCAT_WS to omit null values:

SELECT CONCAT_WS(',', col1, col2, col3, ....)
FROM yourtable

Dynamic Column Concatenation

If manual column specification is inconvenient, consider employing a dynamic query to obtain all column names:

SELECT `column_name` 
FROM   `information_schema`.`columns` 
WHERE  `table_schema`=DATABASE() 
       AND `table_name`='yourtable'

Combine this result with GROUP_CONCAT to generate a comma-separated list of quoted column names:

GROUP_CONCAT(CONCAT('`', column_name, '`'))

Complete Dynamic Query

With these elements, you can construct a dynamic query:

SELECT
  CONCAT(
    'SELECT CONCAT_WS(\'\',',
    GROUP_CONCAT(CONCAT('`', column_name, '`') ORDER BY column_name),
    ') AS all_columns FROM yourtable;')
FROM   `information_schema`.`columns` 
WHERE  `table_schema`=DATABASE() 
       AND `table_name`='yourtable'
INTO @sql;

This query generates a string akin to:

SELECT CONCAT_WS('', col1, col2, col3, ....) AS all_columns FROM yourtable

Execute this string using:

PREPARE stmt FROM @sql;
EXECUTE stmt;

This approach eliminates the need for manual column listing, ensuring dynamic and scalable concatenation.

The above is the detailed content of How to concatenate MySQL columns without listing all columns?. For more information, please follow other related articles on the PHP Chinese website!