mysql sql format support keepComments.

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java

@@ -73,6 +73,11 @@ public class MySqlExprParser extends SQLExprParser {
         this.lexer.nextToken();
     }
 
+    public MySqlExprParser(String sql, boolean keepComments){
+        this(new MySqlLexer(sql, keepComments, keepComments));
+        this.lexer.nextToken();
+    }
+
     public SQLExpr relationalRest(SQLExpr expr) {
         if (identifierEquals("REGEXP")) {
             lexer.nextToken();

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlLexer.java

@@ -75,6 +75,13 @@ public class MySqlLexer extends Lexer {
         super.keywods = DEFAULT_MYSQL_KEYWORDS;
     }
 
+    public MySqlLexer(String input, boolean skipComment, boolean keepComments){
+        super(input, skipComment);
+        this.skipComment = skipComment;
+        this.keepComments = keepComments;
+        super.keywods = DEFAULT_MYSQL_KEYWORDS;
+    }
+
     public void scanSharp() {
         if (ch != '#') {
             throw new ParserException("illegal stat");

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java

@@ -87,6 +87,10 @@ public class MySqlSelectParser extends SQLSelectParser {
 
         MySqlSelectQueryBlock queryBlock = new MySqlSelectQueryBlock();
 
+        if (lexer.hasComment() && lexer.isKeepComments()) {
+            queryBlock.addBeforeComment(lexer.readAndResetComments());
+        }
+
         if (lexer.token() == Token.SELECT) {
             lexer.nextToken();
 

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java

@@ -231,6 +231,10 @@ public class MySqlStatementParser extends SQLStatementParser {
         super(new MySqlExprParser(sql));
     }
 
+    public MySqlStatementParser(String sql, boolean keepComments) {
+        super(new MySqlExprParser(sql, keepComments));
+    }
+
     public MySqlStatementParser(Lexer lexer) {
         super(new MySqlExprParser(lexer));
     }

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -206,8 +206,8 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     }
 
     public boolean visit(MySqlSelectQueryBlock x) {
-        if (x.getOrderBy() != null) {
-            x.getOrderBy().setParent(x);
+        if ((!isParameterized()) && isPrettyFormat() && x.hasBeforeComment()) {
+            printComment(x.getBeforeCommentsDirect(), "\n");
         }
 
         print0(ucase ? "SELECT " : "select ");