feat: add solutions to lc problem: No.1440

No.1440.Evaluate Boolean Expression

Author: yanglbme

solution/1400-1499/1440.Evaluate Boolean Expression/README.md

@@ -86,7 +86,32 @@ Result 表:
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+select
+    left_operand,
+    operator,
+    right_operand,
+    case
+        when (
+            (
+                e.operator = '='
+                and v1.value = v2.value
+            )
+            or (
+                e.operator = '>'
+                and v1.value > v2.value
+            )
+            or (
+                e.operator = '<'
+                and v1.value < v2.value
+            )
+        ) then 'true'
+        else 'false'
+    end value
+from
+    Expressions e
+    left join Variables v1 on e.left_operand = v1.name
+    left join Variables v2 on e.right_operand = v2.name
 ```
 
 <!-- tabs:end -->

solution/1400-1499/1440.Evaluate Boolean Expression/README_EN.md

@@ -88,7 +88,32 @@ As shown, you need to find the value of each boolean expression in the table usi
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+select
+    left_operand,
+    operator,
+    right_operand,
+    case
+        when (
+            (
+                e.operator = '='
+                and v1.value = v2.value
+            )
+            or (
+                e.operator = '>'
+                and v1.value > v2.value
+            )
+            or (
+                e.operator = '<'
+                and v1.value < v2.value
+            )
+        ) then 'true'
+        else 'false'
+    end value
+from
+    Expressions e
+    left join Variables v1 on e.left_operand = v1.name
+    left join Variables v2 on e.right_operand = v2.name
 ```
 
 <!-- tabs:end -->

solution/1400-1499/1440.Evaluate Boolean Expression/Solution.sql

@@ -0,0 +1,26 @@
+# Write your MySQL query statement below
+select
+    left_operand,
+    operator,
+    right_operand,
+    case
+        when (
+            (
+                e.operator = '='
+                and v1.value = v2.value
+            )
+            or (
+                e.operator = '>'
+                and v1.value > v2.value
+            )
+            or (
+                e.operator = '<'
+                and v1.value < v2.value
+            )
+        ) then 'true'
+        else 'false'
+    end value
+from
+    Expressions e
+    left join Variables v1 on e.left_operand = v1.name
+    left join Variables v2 on e.right_operand = v2.name