Question

我处于可以多次出现同一条记录的情况。

问题在于某些字段可能会丢失，这由该字段中的值-1表示。该字段的值将是正确的值或-1。正确的值将始终为正。问题是我事先不知道哪些字段会丢失，并且每条记录的丢失字段集可能不同。我的目标是在数据库中有一个最终条目，该条目汇集所有正确的值。

我想要做的是插入和替换那些值增加的列。鉴于唯一可能的值是-1并且正确的值是正数，这应确保我最终得到尽可能多的正确行（当然，可能从所有记录中省略了一些列。） / p>

conn = sqlite3.connect('example.db')
c = conn.cursor()
c.execute('''CREATE table IF NOT EXISTS SearchTable ([Owner] INTEGER  
PRIMARY KEY, [Val1] INT, [Val2] INT)''')
c.execute("""INSERT OR REPLACE INTO SearchTable (Val1, Val2) values(-1, 
5)""")
c.execute("""INSERT OR REPLACE INTO SearchTable (Owner, Val1, Val2) 
values(1, 7, -1)""")

以上代码是我的尝试（我对sql还是很陌生），显然这是错误的，它会更新两个列，无论它们的当前值如何，但由于Val1已增加，因此它只应更新Val1，而Val2应该保持不变，因为它减少了。

以下问题似乎在询问类似问题，但在这种情况下，您有一个完整的数据集可与之进行比较，而您不知道在我的情况下哪些记录是完整的（如果有的话）。因此，我无法对此问题一概而论。

How to conditionally INSERT OR REPLACE a row in SQLite?

这个我真的根本听不懂答案，但是也许在解决我的问题时会有所帮助。

SQLite conditional insert or replace

Answer 1

我相信以下是您想做的事情。

如果您具有3.24.0或更高版本的SQlite，则可以使用 UPSERT （更新或插入）

例如：-

DROP TABLE IF EXISTS SearchTable;
CREATE TABLE IF NOT EXISTS SearchTable ([Owner] INTEGER PRIMARY KEY, [Val1] INT, [Val2] INT);

INSERT INTO SearchTable (Owner,Val1,Val2) VALUES(null,-1,5) 
    ON CONFLICT(Owner) DO UPDATE 
        SET 
            Val1 = CASE WHEN Val1 < 0 AND -1 /*<<<<<<<<<< value for val1 */ > 0 THEN -1 /*<<<<<<<<<< value for val1 */ ELSE Val1 END, 
            Val2 = CASE WHEN Val2 < 0 AND 5 /*<<<<<<<<<< value for val2 */ > 0 THEN 5 /*<<<<<<<<<< value for val2 */ ELSE Val2 END
;
INSERT INTO SearchTable (Owner,Val1,Val2) VALUES(1,7,-1) 
    ON CONFLICT(Owner) DO UPDATE 
        SET Val1 = CASE WHEN Val1 < 0 AND 7 /*<<<<<<<<< value for val1 */ > 0 THEN 7 /*<<<<<<<<<< value for val1 */ ELSE Val1 END, 
        Val2 = CASE WHEN Val2 < 0 AND 5 /*<<<<<<<<<<< value for val2 */ > 0 THEN 5 /*<<<<<<<<<< value for val2 */ ELSE Val2 END
    ;

结果：-

sqlite> INSERT INTO SearchTable (Owner,Val1,Val2) VALUES(null,-1,5) ON CONFLICT(Owner) DO UPDATE SET Val1 = CASE WHEN Val1 < 0 AND -1 > 0 THEN -1 ELSE Val1 END , Val2 = CASE WHEN Val2 < 0 AND 5 > 0 THEN 5 ELSE Val2 END;
sqlite> select * from SearchTable;
1|-1|5
sqlite> INSERT INTO SearchTable (Owner,Val1,Val2) VALUES(1,7,-1) ON CONFLICT(Owner) DO UPDATE SET Val1 = CASE WHEN Val1 < 0 AND 7 > 0 THEN 7 ELSE Val1 END, Val2 = CASE WHEN Val2 < 0 AND 5 > 0 THEN 5 ELSE Val2 END;
sqlite> select * from SearchTable;
1|7|5

注意下一个示例包含更多说明性说明，其中许多说明均适用。

如果SQlite版本低于3.24.0，请考虑：-

DROP TABLE IF EXISTS SearchTable;
CREATE TABLE IF NOT EXISTS SearchTable ([Owner] INTEGER PRIMARY KEY, [Val1] INT, [Val2] INT);

-- First Insert (null -1,5)
INSERT OR REPLACE INTO SearchTable ([Owner],Val1, Val2) VALUES(null /* owner null if first insert and auto generated value required, else known owner value */, 
    -- Handle VAL1 column
        CASE
            -- if no owner matching supplied value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = null /*<<<<<<<<<< owner value */) IS NULL THEN -1 /* 1st value */
            -- if current value is -1 then use supplied value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = null /*<<<<<<<<< owner value */) = -1 THEN -1 /* 1st value */
            -- if current value is o or greater then use current value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = null /*<<<<<<<<< owner value */) > -1 THEN (SELECT Val1 FROM SearchTable WHERE [owner] = null /*<<<<<<<<<< owner value */)
        END,
        -- Handle Val2 Column
        CASE 
            -- if no owner matching supplied value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = null /*<<<<<<<<<< owner value */) IS NULL THEN 5 /* 2nd value */
            -- if current value is -1 then use supplied value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = null /*<<<<<<<<< owner value */) = -1 THEN 5 /* 2nd value */
            -- if current value is 0 or greater then use current value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = null /*<<<<<<<<< owner value */) > -1 THEN (SELECT Val2 FROM SearchTable WHERE [owner] = null /*<<<<<<<<<< owner value */)
        END
);
-- Show result 1
SELECT * FROM SearchTable;

-- Second Insert (1,7,-1) !!!!Assumes that 5 should change to -1
INSERT OR REPLACE INTO SearchTable ([Owner],Val1, Val2) VALUES(1 /* owner null if first insert and auto generated value required, else known owner value */, 
    -- Handle VAL1 column
        CASE
            -- if no owner matching supplied value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<<< owner value */) IS NULL THEN 7 /* 1st value */
            -- if current value is -1 then use supplied value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<< owner value */) = -1 THEN 7 /* 1st value */
            -- if current value is 0 or greater then use current value
            WHEN (SELECT Val1 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<< owner value */) > -1 THEN (SELECT Val1 FROM SearchTable WHERE [owner] = null /*<<<<<<<<<< owner value */)
        END,
        -- Handle Val2 Column
        CASE 
            -- if no owner matching supplied value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<<< owner value */) IS NULL THEN -1 /* 2nd value */
            -- if current value is -1 then use supplied value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<< owner value */) = -1 THEN -1 /* 2nd value */
            -- if current value is 0 or greater then use current value
            WHEN (SELECT Val2 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<< owner value */) > -1 THEN (SELECT Val2 FROM SearchTable WHERE [owner] = 1 /*<<<<<<<<<< owner value */)
        END
);
-- Show result 2
SELECT * FROM SearchTable;

这最初使用3个提供的值（[owner]，val1和val1） null，-1和5 来添加行（所有者的值为null）：-

第二种用法使用值（[所有者]，val1和val1） 1 ， 7 和 -1

Val2未更新
- 我想要做的是插入和替换这些列其价值增加了。假设唯一可能的值为-1 正确的值是正数，这应该确保我结束尽可能多的正确行（当然可能是删除所有记录中的某些列。）

按照：-

SQlite在每个列值大于当前值时插入或替换条件

1 个答案: