使用更新或插入语句添加到整数值

Question

我正在尝试在 Firebird 2.5 中创建一个 SQL 语句，以便通过在记录存在时添加到整数来更新整数数量，或者只是插入一个新行。我似乎无法找到关于添加某个数量（如果已经存在）的具体问题的真正答案。

我能想到的SQL如下：

UPDATE OR INSERT INTO Pencils(Number, Location, Quantity)
VALUES('12345678/90', 'TOP', 20)
MATCHING(Number, Location);

所以如果有匹配的记录，我想在实际 20 数量的基础上增加一定数量。

就像我对UPDATE 声明所做的那样：

UPDATE Pencils SET Quantity = Quantity + 20 WHERE Number = '12345678/90' 

是否有可能使用UPDATE OR INSERT 语句实现这样的结果，还是有其他方法？ . .

编辑： 使用 IBExpert / Delphi 使用参数查询的解决方案

MERGE INTO Pencils AS Dest
USING (SELECT CAST(:myNumb as varchar(30))  AS Number,
              CAST(:myLoca as varchar(10))  AS Location,
              CAST(:myQuan as integer)  AS Quantity
        FROM RDB$DATABASE) Src
    ON (Dest.Number = Src.Number AND Dest.Location = Src.Location)
WHEN MATCHED THEN
   UPDATE SET Dest.Quantity = Dest.Quantity + Src.Quantity
WHEN NOT MATCHED THEN
   INSERT (Number, Location, Quantity) VALUES (Src.Number, Src.Location, Src.Quantity);

Answer 1

使用 Firebird 的 MERGE 处理复杂的 UPSERT：

MERGE INTO Pencils AS Dest
USING (SELECT '12345678/90' AS Number,
              'TOP'         AS Location,
              20            As Quantity
         FROM RDB$DATABASE) Src
   ON (Dest.Number = Src.Number AND Dest.Location = Src.Location)
WHEN MATCHED THEN
   UPDATE SET Dest.Quantity = Dest.Quantity + 10
WHEN NOT MATCHED THEN
   INSERT (Number, Location, Quantity) VALUES (Src.Number, Src.Location, Src.Quantity);

这里唯一的复杂性是您在更新时动态计算的Quantity。如果您只是用静态值覆盖现有记录，则可以更简洁地使用 UPDATE OR INSERT。

示例：

SQL> SELECT * FROM Pencils;

NUMBER               QUANTITY LOCATION         
================ ============ ================ 
123                         5 TOP              
123                        10 MID              

SQL> MERGE INTO Pencils AS Dest
CON> USING (SELECT '123' AS Number, 'TOP' AS Location, 20 As Quantity
CON> FROM RDB$DATABASE) Src ON (Dest.Number = Src.Number AND Dest.Location = Src.Location)
CON> WHEN MATCHED THEN
CON>    UPDATE SET Dest.Quantity = Dest.Quantity + 10
CON> WHEN NOT MATCHED THEN
CON>    INSERT (Number, Location, Quantity) VALUES (Src.Number, Src.Location, Src.Quantity);

SQL> SELECT * FROM Pencils;

NUMBER               QUANTITY LOCATION         
================ ============ ================ 
123                        15 TOP              
123                        10 MID              

SQL> SELECT * FROM Pencils;

NUMBER               QUANTITY LOCATION         
================ ============ ================ 
123                         5 TOP              
123                        10 MID              

SQL> MERGE INTO Pencils AS Dest
CON> USING (SELECT '123' AS Number, 'TOP' AS Location, 20 As Quantity
CON> FROM RDB$DATABASE) Src ON (Dest.Number = Src.Number AND Dest.Location = Src.Location)
CON> WHEN MATCHED THEN
CON>    UPDATE SET Dest.Quantity = Dest.Quantity + 10
CON> WHEN NOT MATCHED THEN
CON>    INSERT (Number, Location, Quantity) VALUES (Src.Number, Src.Location, Src.Quantity);

SQL> SELECT * FROM Pencils;

NUMBER               QUANTITY LOCATION         
================ ============ ================ 
123                        15 TOP              
123                        10 MID              
123                        20 BOT       

Answer 2

当然可以使用更新或插入。 但是您必须重复您的键值，这会使您的查询变得脆弱（仅更改两个值之一 - 并且您的查询行为不端）

UPDATE OR INSERT 
   INTO Pencils(Number, Location, Quantity)
VALUES( '12345678/90', 'TOP', 
  20 + coalesce(
        ( Select Quantity 
             From Pencils 
          where Number = '12345678/90' 
            and Location = 'TOP' )
       ,0 )
       )
MATCHING(Number, Location);

在 Delphi 中，大多数库不支持具有相同名称的多个 SQL 参数，因此您可能必须实际创建两个参数，名称相似但名称清晰，才能使这种方法起作用。

所以，总而言之，MERGE 会是更好的方法，更安全。但为了完整起见，这也应该有效。

select rdb$get_context('SYSTEM', 'ENGINE_VERSION') as version
     , rdb$character_set_name
from rdb$database;

版本 | RDB$CHARACTER_SET_NAME :-------- | :------------------------------------------------ -------------------------------------------------- ---------------------- 3.0.5 | UTF8

create table Pencils( Number varchar(20), Location varchar(10), Quantity int,
   constraint pk_pens primary key (number, location) )

✓

INSERT INTO Pencils(Number, Location, Quantity)
VALUES('12345678/90', 'TOP', 13)

1 行受影响

INSERT INTO Pencils(Number, Location, Quantity)
VALUES('12345678/90', 'MID', 7)

1 行受影响

select * from pencils

号码 |位置 |数量 :------------ | :------- | --------: 12345678/90 |顶部 | 13 12345678/90 |中 | 7

UPDATE OR INSERT 
   INTO Pencils(Number, Location, Quantity)
VALUES( '12345678/90', 'TOP', 
  20 + coalesce(
          (Select Quantity 
             From Pencils 
          where Number = '12345678/90' 
            and Location = 'TOP')
       ,0 )
       )
MATCHING(Number, Location);

1 行受影响

UPDATE OR INSERT 
   INTO Pencils(Number, Location, Quantity)
VALUES( '12345678/90', 'BOTTOM', 
  20 + coalesce(
          (Select Quantity 
             From Pencils 
          where Number = '12345678/90' 
            and Location = 'BOTTOM')
       ,0 )
       )
MATCHING(Number, Location);

1 行受影响

select * from pencils

号码 |位置 |数量 :------------ | :------- | --------: 12345678/90 |顶部 | 33 12345678/90 |中 | 7 12345678/90 |底部 | 20

db小提琴here

---

@pilcrow 提问：为了完整起见，您能否显示 UPDATE OR INSERT，其中新插入的数量不是简单地“零 + 增量”？

基于表达式中的NULL 语义，只需像这样修改查询的中间部分：

.........
VALUES( '12345678/90', 'TOP', 
  coalesce( 20 + -- increment when found
        ( Select Quantity 
             From Pencils 
          where Number = '12345678/90' 
            and Location = 'TOP' )
       ,  -15 /* new value when not found */ )
       )
.......