發行檢索特定的SQL行

Question

我想在我的數據庫中檢索特定行，設置是這樣的：

CREATE TABLE "Rules" ("credit" BOOL NOT NULL , "debit" BOOL NOT NULL , "product_code" INTEGER, "frequency" INTEGER, "percentage" FLOAT, "limit" FLOAT, "below" BOOL, "above" BOOL, "price" FLOAT) 

我的代碼是：

class Process_Rules 

    def initialize() 
      @rules = Array.new() {Array.new()} 
    end 

    def process() 

     db = SQLite3::Database.open "Checkout.sqlite" 
     ############################################# 

     productRules = db.execute "SELECT product_code FROM Rules WHERE product_code NOT NULL" 

     @rules.push([]) 

     for i in 0..productRules.length 

      @rules[0].push(productRules[i]) 
     end 

     ############################################# 

     limitRules = db.execute "SELECT limit FROM Rules" #ERRORSOME HERE, PREVIOUS SQL STATEMENT EXECUTES FINE 

     ############################################# 

     db.close() 
    end 
end 

錯誤：

in 'initialize': near 'limit': syntax error (SQLite3::SQLException) 

Answer 1

由於LIMIT是關鍵字，因此您必須引用它：

SELECT "limit" FROM Rules