can I use a variable to specify OUTFILE in mysql

Question

Is there a way to do something like the following ? which doesn't work but shows what I want to do

SET @OutputPath = '/Users/jo/Documents'
SET @fullOutputPath = CONCAT(@OutputPath,'/','filename.csv')
SET @fullOutputPath2 = CONCAT(@OutputPath,'/','filename2.csv')

SELECT * INTO OUTFILE @fullOutputPath
FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '"'
FROM database.tableName;

SELECT * INTO OUTFILE @fullOutputPath2
FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '"'
FROM database.tableName2;

Answer 1

Edit: Saving data(e.g. a table) into file without using variable (only constant values)

-- folder_path could could be like => c:/users/sami
-- choose the directory/folder already available in system
-- and make sure you have access to write the file there

SELECT * INTO OUTFILE 'folder_path/filename.csv'
FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '"'
FROM database.tableName;

Now using variable

Whenever you have to use a variable name in sql, you need dynamic sql (which is applicable in stored procedures only, neither in simple sql query nor in triggers or functions)

SET @OutputPath := 'Users/jo/Documents'; //or any folder_path
SET @fullOutputPath := CONCAT(@OutputPath,'/','filename.csv');
SET @fullOutputPath2 := CONCAT(@OutputPath,'/','filename2.csv');

set @q1 := concat("SELECT * INTO OUTFILE ",@fullOutputPath,
" FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '\"'
FROM database.tableName");

set @q2 := concat("SELECT * INTO OUTFILE ",@fullOutputPath2,
" FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '\"'
FROM database.tableName2");

prepare s1 from @q1;
execute s1;deallocate prepare s1;

prepare s1 from @q2;
execute s1;deallocate prepare s1;

As you had both ' and " in your query already, so I concatenated your query using " and used \ to escape your original " to ensure its use as a literal character and not used for concatenation

I just told the use of variable in sql. First You should make sure if your query works like example at the top (without using variable)

Conclusion: If your above query works fine then my told dynamic sql will work as well given that you are using it in some stored procedure.

Answer 2

I have a low carma so I'm posting an answer that should go as a comment to Sami's post - you need to enclose the file name by quotes (note added ' before and after @fullOutputPath):

set @q1 := concat("SELECT * INTO OUTFILE '",@fullOutputPath,
"' FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '\"'
FROM database.tableName");

Answer 3

If you want to do this from bash, i.e. export some data from mysql in csv to a file with dynamic name, it maybe easier and more readable like the following.

The SQL with embedded bash variables:

where (e.timestamp >= ${begin_ts} and e.timestamp < ${end_ts}) order by ed.timestamp ASC ) a
INTO OUTFILE '${export_path}' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n';

And the bash script that runs the sql file. Notice the envsubst command that evaluates the sql script and substitutes the variables.

#!/bin/bash
mysql_db="dbname"
mysql_user="mysqlpass"
mysql_pass="password"
export_path="./data.csv"
begin_ts="1478278490"
current_ts=$(date +%s -u)

sql=`export_path=${export_path} begin_ts=${last_ts} end_ts=${current_ts} envsubst < export.sql`
mysql $mysql_db -u $mysql_user -p$mysql_pass -e"${sql}"