SQL: Fix POWER doc, add test. (#4953)

docs/content/querying/sql.md

@@ -108,7 +108,7 @@ Numeric functions will return 64 bit integers or 64 bit floats, depending on the
 |`FLOOR(expr)`|Floor.|
 |`LN(expr)`|Logarithm (base e).|
 |`LOG10(expr)`|Logarithm (base 10).|
-|`POW(expr, power)`|expr to a power.|
+|`POWER(expr, power)`|expr to a power.|
 |`SQRT(expr)`|Square root.|
 |`TRUNCATE(expr[, digits])`|Truncate expr to a specific number of decimal digits. If digits is negative, then this truncates that many places to the left of the decimal point. Digits defaults to zero if not specified.|
 |`TRUNC(expr[, digits])`|Synonym for `TRUNCATE`.|

sql/src/test/java/io/druid/sql/calcite/expression/ExpressionsTest.java

@@ -201,6 +201,16 @@ public class ExpressionsTest
     );
   }
 
+  @Test
+  public void testPower()
+  {
+    testExpression(
+        rexBuilder.makeCall(SqlStdOperatorTable.POWER, inputRef("a"), integerLiteral(2)),
+        DruidExpression.fromExpression("pow(\"a\",2)"),
+        100.0
+    );
+  }
+
   @Test
   public void testFloor()
   {