feat: add DataType::Char and add LEN to Describe

[KKould]

What problem does this PR solve?

let _ = fnck_sql
    .run("CREATE TABLE TABLE_E021_02_01_05 ( ID INT PRIMARY KEY, A CHAR ( 8 ) )")
    .await?;
let (schema, tuples) = fnck_sql.run("describe TABLE_E021_02_01_05").await?;
println!("{}", create_table(&schema, &tuples));

+-------+---------+-----+-------+---------+---------+
| FIELD | TYPE    | LEN | NULL  | Key     | DEFAULT |
+===================================================+
| id    | INTEGER | 4   | false | PRIMARY | null    |
|-------+---------+-----+-------+---------+---------|
| a     | CHAR    | 8   | true  | EMPTY   | null    |
+-------+---------+-----+-------+---------+---------+

on mysql

mysql> insert into T1 (A) VALUES('      abc   ');
Query OK, 1 row affected (0.00 sec)

mysql> select * from T1;
+-----------+
| A         |
+-----------+
| abc       |
|       abc |
+-----------+
2 rows in set (0.00 sec)

Issue link: #130

Code changes

• Has Rust code change
• Has CI related scripts change

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Note for reviewer

[crwen]

select * from t;
ERROR:  Unsupported Datatype CHAR

You need add LogicalType::Char to into_pg_type method

[crwen]

maybe use trim_end()

String::from_utf8(bytes.to_owned()).unwrap().trim_end();

and the link is too long 😂

[KKould]

I tried it and it will make ' foo ' become 'foo', but it should be ' foo' in mysql

[crwen]

trim_end only remove trailing whitespace. You might used trim().

[KKould]

trim_end only remove trailing whitespace. You might used trim().

oh, you are right, but I found that trim_end() returns &str, which may cause String to be copied again.