Merging upstream version 20.9.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/sqlglot/optimizer/simplify.py b/sqlglot/optimizer/simplify.py
index f53023c..25d4e75 100644
--- a/sqlglot/optimizer/simplify.py
+++ b/sqlglot/optimizer/simplify.py
@@ -100,6 +100,7 @@ def simplify(
         node = simplify_parens(node)
         node = simplify_datetrunc(node, dialect)
         node = sort_comparison(node)
+        node = simplify_startswith(node)
 
         if root:
             expression.replace(node)
@@ -776,6 +777,26 @@ def simplify_conditionals(expression):
     return expression
 
 
+def simplify_startswith(expression: exp.Expression) -> exp.Expression:
+    """
+    Reduces a prefix check to either TRUE or FALSE if both the string and the
+    prefix are statically known.
+
+    Example:
+        >>> from sqlglot import parse_one
+        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
+        'TRUE'
+    """
+    if (
+        isinstance(expression, exp.StartsWith)
+        and expression.this.is_string
+        and expression.expression.is_string
+    ):
+        return exp.convert(expression.name.startswith(expression.expression.name))
+
+    return expression
+
+
 DateRange = t.Tuple[datetime.date, datetime.date]
 
 
@@ -1160,7 +1181,7 @@ def gen(expression: t.Any) -> str:
 GEN_MAP = {
     exp.Add: lambda e: _binary(e, "+"),
     exp.And: lambda e: _binary(e, "AND"),
-    exp.Anonymous: lambda e: f"{e.this} {','.join(gen(e) for e in e.expressions)}",
+    exp.Anonymous: lambda e: f"{e.this.upper()} {','.join(gen(e) for e in e.expressions)}",
     exp.Between: lambda e: f"{gen(e.this)} BETWEEN {gen(e.args.get('low'))} AND {gen(e.args.get('high'))}",
     exp.Boolean: lambda e: "TRUE" if e.this else "FALSE",
     exp.Bracket: lambda e: f"{gen(e.this)}[{gen(e.expressions)}]",