MySQL表視圖數據類型

Question

我正在嘗試將數據類型bigint（37）更改為int（11）。 我嘗試了幾種方法CAST或CONVERT，但未成功結束。

如何在此表VIEW中更改數據類型？ 請。 謝謝。

CREATE OR REPLACE VIEW gtemp_view AS
    SELECT
    d1.Week AS Week1,
    d2.Week AS Week2,
    IF( ABS(d1.dt1-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt4)=0,1,0) AS mcount
FROM gtemp AS d1 , gtemp AS d2 WHERE d1.Week IS NOT NULL AND d2.Week IS NOT NULL AND d1.Week > d2.Week order by Week1 DESC, Week2 DESC limit 200000;

Answer 1

如果您不想在視圖架構中看到INT37，則可以嘗試使用顯式強制類型轉換為unsigned

CREATE OR REPLACE VIEW gtemp_view AS
    SELECT
    d1.Week AS Week1,
    d2.Week AS Week2,
    cast( 
    (IF( ABS(d1.dt1-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt1-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt2-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt3-d2.dt4)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt1)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt2)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt3)=0,1,0) +
    IF( ABS(d1.dt4-d2.dt4)=0,1,0)) 
    AS UNIGNED) mcount
FROM gtemp AS d1 , gtemp AS d2 
WHERE d1.Week IS NOT NULL 
AND d2.Week IS NOT NULL 
AND d1.Week > d2.Week 
order by Week1 DESC, Week2 DESC limit 200000;

無論如何，強制轉換應該以幾種方式影響性能。相反，INT37數據類型不應導致明顯的性能下降