[MySql] Support convert to double/float type for cast/convert function (#3858)

Author: harveyyue

sql/mysql/Positive-Technologies/MySqlParser.g4

@@ -2288,9 +2288,9 @@ collectionOptions
 convertedDataType
     :
     (
-      typeName=(BINARY| NCHAR) lengthOneDimension?
+      typeName=(BINARY | NCHAR | FLOAT) lengthOneDimension?
       | typeName=CHAR lengthOneDimension? (charSet charsetName)?
-      | typeName=(DATE | DATETIME | TIME | JSON | INT | INTEGER)
+      | typeName=(DATE | DATETIME | TIME | YEAR | JSON | INT | INTEGER | DOUBLE)
       | typeName=(DECIMAL | DEC) lengthTwoOptionalDimension?
       | (SIGNED | UNSIGNED) (INTEGER | INT)?
     ) ARRAY?

sql/mysql/Positive-Technologies/examples/ddl_alter.sql

@@ -3,6 +3,8 @@
 alter table ship_class add column ship_spec varchar(150) first, add somecol int after start_build;
 alter table t3 add column (c2 decimal(10, 2) comment 'comment`' null, c3 enum('abc', 'cba', 'aaa')), add index t3_i1 using btree (c2) comment 'some index';
 alter table t3 add column (c2 decimal(10, 2), c3 int);
+ALTER TABLE `deals` ADD INDEX `idx_custom_field_30c4f4a7c529ccf0825b2fac732bebfd843ed764` ((cast(json_unquote(json_extract(`custom_fields`,_utf8mb4'$."30c4f4a7c529ccf0825b2fac732bebfd843ed764".value')) as DOUBLE)));
+ALTER TABLE `deals` ADD INDEX `idx_custom_field_30c4f4a7c529ccf0825b2fac732bebfd843ed764` ((cast(json_unquote(json_extract(`custom_fields`,_utf8mb4'$."30c4f4a7c529ccf0825b2fac732bebfd843ed764".value')) as FLOAT)));
 alter table t3 alter index t3_i1 invisible;
 alter table t3 alter index t3_i1 visible;
 alter table t3 rename index t3_i1 to t3_i2;

sql/mysql/Positive-Technologies/examples/ddl_create.sql

@@ -287,6 +287,8 @@ create index index5 on antlr_tokens(token(30) asc) algorithm default;
 create index index6 on antlr_tokens(token(30) asc) algorithm default lock default;
 create index index7 on antlr_tokens(token(30) asc) lock default algorithm default;
 create index index8 on t1(col1) comment 'test index' using btree;
+CREATE INDEX `idx_custom_field_30c4f4a7c529ccf0825b2fac732bebfd843ed764` ON `deals` ((cast(json_unquote(json_extract(`custom_fields`,_utf8mb4'$."30c4f4a7c529ccf0825b2fac732bebfd843ed764".value')) as double)));
+CREATE INDEX `idx_custom_field_d3bb7ad91ba729aaa20df0af037cb7ed8ce3ffc8` ON `deals` ((cast(json_unquote(json_extract(`custom_fields`,_utf8mb4'$."d3bb7ad91ba729aaa20df0af037cb7ed8ce3ffc8".value')) as float)));
 #end
 #begin
 -- Create logfile group