1 files changed, 163 insertions, 0 deletions
diff --git a/sqlglot/dialects/mysql.py b/sqlglot/dialects/mysql.py
new file mode 100644
index 0000000..93800a6
--- /dev/null
+++ b/sqlglot/dialects/mysql.py
@@ -0,0 +1,163 @@
+from sqlglot import exp
+from sqlglot.dialects.dialect import (
+    Dialect,
+    no_ilike_sql,
+    no_paren_current_date_sql,
+    no_tablesample_sql,
+    no_trycast_sql,
+)
+from sqlglot.generator import Generator
+from sqlglot.helper import list_get
+from sqlglot.parser import Parser
+from sqlglot.tokens import Tokenizer, TokenType
+
+
+def _date_trunc_sql(self, expression):
+    unit = expression.text("unit").lower()
+
+    this = self.sql(expression.this)
+
+    if unit == "day":
+        return f"DATE({this})"
+
+    if unit == "week":
+        concat = f"CONCAT(YEAR({this}), ' ', WEEK({this}, 1), ' 1')"
+        date_format = "%Y %u %w"
+    elif unit == "month":
+        concat = f"CONCAT(YEAR({this}), ' ', MONTH({this}), ' 1')"
+        date_format = "%Y %c %e"
+    elif unit == "quarter":
+        concat = f"CONCAT(YEAR({this}), ' ', QUARTER({this}) * 3 - 2, ' 1')"
+        date_format = "%Y %c %e"
+    elif unit == "year":
+        concat = f"CONCAT(YEAR({this}), ' 1 1')"
+        date_format = "%Y %c %e"
+    else:
+        self.unsupported("Unexpected interval unit: {unit}")
+        return f"DATE({this})"
+
+    return f"STR_TO_DATE({concat}, '{date_format}')"
+
+
+def _str_to_date(args):
+    date_format = MySQL.format_time(list_get(args, 1))
+    return exp.StrToDate(this=list_get(args, 0), format=date_format)
+
+
+def _str_to_date_sql(self, expression):
+    date_format = self.format_time(expression)
+    return f"STR_TO_DATE({self.sql(expression.this)}, {date_format})"
+
+
+def _date_add(expression_class):
+    def func(args):
+        interval = list_get(args, 1)
+        return expression_class(
+            this=list_get(args, 0),
+            expression=interval.this,
+            unit=exp.Literal.string(interval.text("unit").lower()),
+        )
+
+    return func
+
+
+def _date_add_sql(kind):
+    def func(self, expression):
+        this = self.sql(expression, "this")
+        unit = expression.text("unit").upper() or "DAY"
+        expression = self.sql(expression, "expression")
+        return f"DATE_{kind}({this}, INTERVAL {expression} {unit})"
+
+    return func
+
+
+class MySQL(Dialect):
+    # https://prestodb.io/docs/current/functions/datetime.html#mysql-date-functions
+    time_mapping = {
+        "%M": "%B",
+        "%c": "%-m",
+        "%e": "%-d",
+        "%h": "%I",
+        "%i": "%M",
+        "%s": "%S",
+        "%S": "%S",
+        "%u": "%W",
+    }
+
+    class Tokenizer(Tokenizer):
+        QUOTES = ["'", '"']
+        COMMENTS = ["--", "#", ("/*", "*/")]
+        IDENTIFIERS = ["`"]
+
+        KEYWORDS = {
+            **Tokenizer.KEYWORDS,
+            "_ARMSCII8": TokenType.INTRODUCER,
+            "_ASCII": TokenType.INTRODUCER,
+            "_BIG5": TokenType.INTRODUCER,
+            "_BINARY": TokenType.INTRODUCER,
+            "_CP1250": TokenType.INTRODUCER,
+            "_CP1251": TokenType.INTRODUCER,
+            "_CP1256": TokenType.INTRODUCER,
+            "_CP1257": TokenType.INTRODUCER,
+            "_CP850": TokenType.INTRODUCER,
+            "_CP852": TokenType.INTRODUCER,
+            "_CP866": TokenType.INTRODUCER,
+            "_CP932": TokenType.INTRODUCER,
+            "_DEC8": TokenType.INTRODUCER,
+            "_EUCJPMS": TokenType.INTRODUCER,
+            "_EUCKR": TokenType.INTRODUCER,
+            "_GB18030": TokenType.INTRODUCER,
+            "_GB2312": TokenType.INTRODUCER,
+            "_GBK": TokenType.INTRODUCER,
+            "_GEOSTD8": TokenType.INTRODUCER,
+            "_GREEK": TokenType.INTRODUCER,
+            "_HEBREW": TokenType.INTRODUCER,
+            "_HP8": TokenType.INTRODUCER,
+            "_KEYBCS2": TokenType.INTRODUCER,
+            "_KOI8R": TokenType.INTRODUCER,
+            "_KOI8U": TokenType.INTRODUCER,
+            "_LATIN1": TokenType.INTRODUCER,
+            "_LATIN2": TokenType.INTRODUCER,
+            "_LATIN5": TokenType.INTRODUCER,
+            "_LATIN7": TokenType.INTRODUCER,
+            "_MACCE": TokenType.INTRODUCER,
+            "_MACROMAN": TokenType.INTRODUCER,
+            "_SJIS": TokenType.INTRODUCER,
+            "_SWE7": TokenType.INTRODUCER,
+            "_TIS620": TokenType.INTRODUCER,
+            "_UCS2": TokenType.INTRODUCER,
+            "_UJIS": TokenType.INTRODUCER,
+            "_UTF8": TokenType.INTRODUCER,
+            "_UTF16": TokenType.INTRODUCER,
+            "_UTF16LE": TokenType.INTRODUCER,
+            "_UTF32": TokenType.INTRODUCER,
+            "_UTF8MB3": TokenType.INTRODUCER,
+            "_UTF8MB4": TokenType.INTRODUCER,
+        }
+
+    class Parser(Parser):
+        STRICT_CAST = False
+
+        FUNCTIONS = {
+            **Parser.FUNCTIONS,
+            "DATE_ADD": _date_add(exp.DateAdd),
+            "DATE_SUB": _date_add(exp.DateSub),
+            "STR_TO_DATE": _str_to_date,
+        }
+
+    class Generator(Generator):
+        NULL_ORDERING_SUPPORTED = False
+
+        TRANSFORMS = {
+            **Generator.TRANSFORMS,
+            exp.CurrentDate: no_paren_current_date_sql,
+            exp.CurrentTimestamp: lambda *_: "CURRENT_TIMESTAMP",
+            exp.ILike: no_ilike_sql,
+            exp.TableSample: no_tablesample_sql,
+            exp.TryCast: no_trycast_sql,
+            exp.DateAdd: _date_add_sql("ADD"),
+            exp.DateSub: _date_add_sql("SUB"),
+            exp.DateTrunc: _date_trunc_sql,
+            exp.StrToDate: _str_to_date_sql,
+            exp.StrToTime: _str_to_date_sql,
+        }