# SERIAL_FULL()

## Function description

`SERIAL_FULL()` is used to serialize a connection string, converting a single or multiple columns/value combination into a binary format, the return type is `VARCHAR`, which is generally used with the [`SERIAL_EXTRACT()`](../../../Functions-and-Operators/Other/serial_extract.md) function. `SERIAL_FULL()` is similar to [`SERIAL()`](serial.md), but `SERIAL_FULL()` retains the NULL value.

## Function Syntax

```text
> SERIAL_FULL(para)
```

## Parameter definition

| Parameters | Description |
| ---- | ---- |
| para | Column/value to serialize |

## Example

```text
create table t1(a varchar(3), b int);
insert into t1 values("ABC",1);
insert into t1 values("DEF",NULL);

mysql> select serial_full(a,b) from t1;--The query returns the result of serialization combined with column a and column b, and retains the NULL value when there is a NULL value
+-------------------------+
| serial_full(a, b) |
+-------------------------+
| FABC : |
| FDEF |
+-------------------------+
2 rows in set (0.00 sec)

mysql> select serial_full(1.2,'world');--Query returns the result of the combination serialization of the value 1.2 and the value hello
+------------------------------+
| serial_full(1.2, world) |
+------------------------------+
| D?
          Fworld |
+------------------------------+
1 row in set (0.01 sec)
```