Joining 3Tables gives duplicates rows in MySQL-CodePudding

i have 3 tables with 81 recrods and similar columns (just one got a column less then others) , here is an example :

when i join the 3 tables using a normal join or an inner join :

SELECT DISTINCT *
FROM target 
INNER JOIN demons ON demons.Year  = target.Year
INNER JOIN violence ON violence.Year = target.Year;

i get duplicated rows like this :

they have the same Month and Year values I want to be able to join them without duplicates according to Year and Month

CodePudding user response：

You would at least need to include a condition to match the month as well as the year:

SELECT *
FROM target 
INNER JOIN demons 
  ON demons.Year = target.Year AND demons.Month = target.Month
INNER JOIN violence 
  ON violence.Year = target.Year AND violence.Month = target.Month