Check for MySQL database from cmd with result code?

Question

I'm trying to make a query from cmd that return 0 if database exists or any other number (for example 1), if it doesn't.

I make the query in this way:

"C:\mysql.exe" --host=localhost --user=root --password=pass --execute="SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = 'DB_Name'"

If exists, it returns a table (and a exit code 0); if it doesn't, it returns nothing (and a exit code 0 too)

I use this on a Inno Setup installer like:

Exec(
  ExpandConstant('{tmp}\mysql.exe'),
  '--host='+eServer.text+' --user='+eUser.text+' --password='+ePass.text+
  ' --port='+ePort.text+
  ' --execute="SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = '+
  ''''+eDBname.text+''''+'"', '', SW_HIDE, ewWaitUntilTerminated, ResultCode); 

if (ResultCode <> 0) then          
    MsgBox('Error when connecting to server', mbError, MB_OK);

So it returns me 0 even if the database doesn't exist.

What about adding --database "dbname" to the arguments? Untested for the moment, but that should fail if the db isn't there, otherwise the query will execute normally. — Michael - sqlbot
– Michael - sqlbot, Commented Aug 4, 2017 at 3:30
It Works, thank you so much, can you put your comment to select as answer? — Angel Montes de Oca
– Angel Montes de Oca, Commented Aug 4, 2017 at 15:12

Michael - sqlbot · Accepted Answer · 2017-08-04 17:24:58Z

2

The mysql CLI supports a --database argument to set the default database before it runs any --execute queries. Setting this value to a nonexistent database (or one for which the user doesn't have the required access) causes the CLI to exit non-zero, because the specified database can't be set as the default.

Add the option in one of these formats:

--database "dbname"
--database="dbname"
-D "dbname"

https://dev.mysql.com/doc/refman/5.7/en/mysql-command-options.html#option_mysql_database

answered Aug 4, 2017 at 17:24

Michael - sqlbot

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