How to Dynamically Concatenate All MySQL Columns?

Dynamically Concatenating All MySQL Columns

In MySQL, concatenating all columns using the * wildcard is not supported. Instead, you need to explicitly specify each column name in the CONCAT() or GROUP_CONCAT() functions.

Explicit Column Concatenation:

You can use the CONCAT() function to concatenate specific columns:

<code class="sql">SELECT CONCAT(col1, col2, col3, ...)
FROM yourtable;</code>

Or, use CONCAT_WS() to concatenate columns with a specified separator, skipping null values:

<code class="sql">SELECT CONCAT_WS(',', col1, col2, col3, ...)
FROM yourtable;</code>

Dynamic Column Concatenation:

To avoid manually specifying column names, you can use a dynamic query to retrieve all column names from the information_schema.columns table:

<code class="sql">SELECT `column_name`
FROM `information_schema`.`columns`
WHERE `table_schema` = DATABASE()
  AND `table_name` = 'yourtable';</code>

Then, use GROUP_CONCAT() to combine these column names:

<code class="sql">GROUP_CONCAT(CONCAT('`', column_name, '`'))</code>

This will result in a comma-separated list of quoted column names, such as:

<code class="sql">`col1`,`col2`,`col3`,`col4`,...</code>

With this, you can create a dynamic query to concatenate all columns:

<code class="sql">SET @sql = CONCAT(
  'SELECT CONCAT_WS(\'\',',
  GROUP_CONCAT(CONCAT('`', column_name, '`') ORDER BY column_name),
  ') AS all_columns FROM yourtable;'
);</code>

Finally, execute the dynamic query:

<code class="sql">PREPARE stmt FROM @sql;
EXECUTE stmt;</code>

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