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@@ -19,9 +19,9 @@ insert into table2 select 3, 70
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```
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table1 | table2
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-------------------------------------------------------
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+-----------------------------------------------------------------------------------------
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id name | id score
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- 1 lee | 1 90
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+ 1 lee | 1 90
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2 zhang | 2 100
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4 wang | 3 70
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```
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@@ -44,8 +44,8 @@ select * from table1 inner join table2 on table1.id = table2.id
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```
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id name id score
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-----------------------------------------
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- 1 lee 1 90
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+-----------------------------------------------------------------------------------------
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+ 1 lee 1 90
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2 zhang 2 100
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```
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@@ -80,8 +80,8 @@ select * from table1 left join table2 on table1.id = table2.id
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```
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id name id score
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-------------------------------------------
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- 1 lee 1 90
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+-----------------------------------------------------------------------------------------
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+ 1 lee 1 90
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2 zhang 2 100
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4 wang NULL NULL
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```
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@@ -102,10 +102,10 @@ select * from table1 right join table2 on table1.id = table2.id
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```
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id name id score
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-------------------------------------------
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- 1 lee 1 90
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+-----------------------------------------------------------------------------------------
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+ 1 lee 1 90
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2 zhang 2 100
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- NULL NULL 3 70
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+ NULL NULL 3 70
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```
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[^注释]: 包含 table2 的所有子句,根据指定条件返回 table1 相应的字段,不符合的以 null 显示
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@@ -124,11 +124,11 @@ select * from table1 full join table2 on table1.id = table2.id
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```
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id name id score
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-------------------------------------------
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- 1 lee 1 90
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+-----------------------------------------------------------------------------------------
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+ 1 lee 1 90
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2 zhang 2 100
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4 wang NULL NULL
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- NULL NULL 3 70
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+ NULL NULL 3 70
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```
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[^注释]: 返回左右连接的和(见上左、右连接)
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@@ -149,14 +149,14 @@ select * from table1 cross join table2
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```
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id name id score
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-------------------------------------------
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- 1 lee 1 90
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+-----------------------------------------------------------------------------------------
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+ 1 lee 1 90
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2 zhang 1 90
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4 wang 1 90
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- 1 lee 2 100
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+ 1 lee 2 100
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2 zhang 2 100
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4 wang 2 100
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- 1 lee 3 70
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+ 1 lee 3 70
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2 zhang 3 70
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4 wang 3 70
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```
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@@ -185,7 +185,7 @@ insert into table3 select 3, null
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```
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table3
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----------------------
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+-----------------------------------------------------------------------------------------
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id score
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1 null
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2 null
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@@ -202,7 +202,7 @@ update b set b.score = a.score from table2 a, table3 b where a.id = b.id
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```
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table3
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----------------------
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+-----------------------------------------------------------------------------------------
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id score
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1 90
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2 100
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@@ -221,9 +221,9 @@ delete from table1 where not exists(select 1 from table2 b where table1.id = b.i
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```
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table1 | table2
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-------------------------------------------------------
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+-----------------------------------------------------------------------------------------
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id name | id score
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- 1 lee | 1 90
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+ 1 lee | 1 90
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2 zhang | 2 100
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4 wang | 3 70
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```
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@@ -232,11 +232,11 @@ delete from table1 where not exists(select 1 from table2 b where table1.id = b.i
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```
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table1 | table2
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-------------------------------------------------------
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+-----------------------------------------------------------------------------------------
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id name | id score
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- 1 lee | 1 90
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+ 1 lee | 1 90
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2 zhang | 2 100
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- | 3 70
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+ | 3 70
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```
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[^注释]: 将 table2 表中未使用的 table1 表编号删除
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@@ -253,11 +253,11 @@ delete from table1 where exists(select 1 from table2 b where table1.id = b.id)
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```
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table1 | table2
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-------------------------------------------------------
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+-----------------------------------------------------------------------------------------
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id name | id score
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4 wang | 1 90
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- | 2 100
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- | 3 70
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+ | 2 100
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+ | 3 70
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```
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[^注释]: 将 table2 表中使用的 table1 表编号删除
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