加入兩個字段

Question

我使用PostgreSQL和試圖加入兩個表上的兩個字段兩個表：

SELECT a.high, a.low, a.stname, a.zipcode, b.bhs, b.street_numb, b.street, b.address, b.zipcode 
FROM bin a 
JOIN zp b 
ON (a.stname = b.street) and (a.low = b.street_numb); 

不過，我收到以下錯誤：

ERROR: operator does not exist: character varying = integer 
LINE 4: on (a.stname = b.street) and (a.low = b.street_numb); 
             ^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. 

我怎麼會是能夠得到正確的結果？

Answer 1

您要求Postgres比較兩種不同類型，character和integer。如果你確定a.low將是數字，

CAST (a.low AS INT) = b.street_numb 

Answer 2

ALTER TABLE ZP ALTER COLUMN street_numb型性格（5）;