修改Ruby代碼PostgreSQL的

Question

我以前使用的sqlite3我的Ruby代碼

工作，它的工作罰款下面的代碼

def existsCheck(db, id) 
    temp = db.exec('SELECT 1 WHERE EXISTS(
     SELECT 1 
     FROM Products 
     WHERE promoID = ? 
    ) ', [id]).length > 0 
end 


def writeDB(db, product) 
    db.exec('INSERT INTO Products (promoID, name, price, shipping, condition, grade, included, not_included, image, time_added) 
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)', [product.promoID, product.name, product.price, product.shipping, product.condition, product.grade, product.included, product.notIncluded, product.image, product.time]) 
end 

PostgreSQL可以不支持「的想法？」還是我做錯了什麼？

Answer 1

從fine PG::Connection manual：

- (PG::Result) exec(sql[, params, result_format ])
- (Object) exec(sql[, params, result_format ]) {|pg_result| ... }
[...]
PostgreSQL的綁定參數被表示爲$1，$1，$2等，SQL查詢的內部。 params數組的第0個元素綁定到$1，第1個元素綁定到$2等。nil被視爲NULL。

所以要使用編號的佔位符PostgreSQL的：

def existsCheck(db, id) 
    temp = db.exec('SELECT 1 WHERE EXISTS(
     SELECT 1 
     FROM Products 
     WHERE promoID = $1 
    ) ', [id]).to_a.length > 0 
    # You'll also need to .to_a the result before you can 
    # treat it as an array... 
end