Merge pull request #9302 from xudong963/new_readme

feat: add README for new sqllogictest framework

Author: BohuTANG

tests/sqllogictests/README.md

@@ -0,0 +1,55 @@
+### Overview
+This is Databend's [sqllogictest](https://www.sqlite.org/sqllogictest/doc/trunk/about.wiki) implementation. It uses [sqllogictest-rs](https://github.com/risinglightdb/sqllogictest-rs) to parse test files and run test cases.
+
+### Usage
+You can directly run the following commands under databend directory
+
+---
+Run all tests under the three handlers(mysql, http, clickhouse) in turn.
+```shell
+cargo run -p sqllogictests
+```
+---
+Run all tests with specific handler.
+```shell
+cargo run -p sqllogictests -- --handlers <handler_name>
+```
+---
+Run tests under specific directory.
+
+```shell
+cargo run -p sqllogictests -- --run_dir <dir_name>
+```
+---
+Run tests under specific file. This is the most commonly used command because users do not need to run all tests at a time and only need to run their newly added test files or test files with changes
+```shell
+cargo run -p sqllogictests -- --run_file <file_name>
+```
+---
+For more information, run help command:
+```shell
+cargo run -p sqllogictests -- --help
+```
+
+### sqllogictest
+Most records are either a statement or a query. A statement is an SQL command that is to be evaluated but from which we do not expect to get results (other than success or failure). A statement might be a CREATE TABLE or an INSERT or an UPDATE or a DROP INDEX. A query is an SQL command from which we expect to receive results. The result set might be empty.
+
+A statement record begins with one of the following two lines:
+```
+statement ok
+statement error <error info>
+```
+The SQL command to be evaluated is found on the second and all subsequent liens of the record. Only a single SQL command is allowed per statement. The SQL should not have a semicolon or other terminator at the end.
+
+A query record begins with a line of the following form:
+```
+# comments
+query <type_string> <sort_mode> <label>
+<sql_query>
+----
+<expected_result>
+```
+The SQL for the query is found on second an subsequent lines of the record up to first line of the form "----" or until the end of the record. Lines following the "----" are expected results of the query, one value per line. If the "----" and/or the results are omitted, then the query is expected to return an empty set.
+
+For more information about arguments, such as <type_string>, <sort_mode>, <label> please refer to [sqllogictest](https://www.sqlite.org/sqllogictest/doc/trunk/about.wiki).
+