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[Feature](function) Support function DEFAULT #3029

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[Feature](function) Support function DEFAULT
linrrzqqq Oct 30, 2025
410caab
add PI && E
linrrzqqq Nov 2, 2025
1b4a5ea
fix
linrrzqqq Nov 5, 2025
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164 changes: 164 additions & 0 deletions docs/sql-manual/sql-functions/scalar-functions/other-functions/default.md
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---
{
"title": "DEFAULT",
"language": "en"
}
---

## Description

Returns the default value of a specific column in the table. If the column has no default value, an error is thrown.

This function behaves consistently with the [DEFAULT function](https://dev.mysql.com/doc/refman/8.4/en/miscellaneous-functions.html#function_default) in MySQL.

## Syntax

```sql
DEFAULT(<column>)
```

## Parameters

| Parameter | Description |
| ---------- | ---------------------------------------------------------------------------------------------------------- |
| `<column>` | The column for which to query the default value. Only columns are accepted; otherwise, an error is thrown. |

## Return Value

Constant default values(include `PI`, `E`):
- If a default value is set, returns the corresponding default value.
- If no default value is set and the column is not NOT NULL, returns NULL.
- If no default value is set and the column is NOT NULL, throws an error.

Non-constant default values (`CURRENT_TIMESTAMP`, `CURRENT_DATE`):
- If the column is not NOT NULL, returns NULL.
- If the column is NOT NULL, returns the minimum value of the corresponding type `0000-01-01 00:00:00` or `0000-01-01`.

Special Cases:
- If the input column is of an aggregate type (`HLL`, `BITMAP`, `QUANTILE_STATE`), throws an error.
- Input parameters are only allowed for columns. If the input is a constant (including NULL) or an expression, throws an error.

[Doris supported default value related parameters](https://doris.apache.org/docs/dev/sql-manual/sql-statements/table-and-view/table/CREATE-TABLE#column-default-value-related-parameters)

## Examples

1. Non-aggregate type constant default value example
```sql
-- setup
-- Columns without explicitly specified DEFAULT values accept only NULL as default
-- ARRAY type default values accept only `[]` and NULL
CREATE TABLE test_default_scalar (
c_bool BOOLEAN NULL DEFAULT 1,
c_tinyint TINYINT NULL DEFAULT 7,
c_smallint SMALLINT NULL DEFAULT 32000,
c_int INT NULL DEFAULT 2147483647,
c_bigint BIGINT NULL DEFAULT 9223372036854775807,
c_largeint LARGEINT NULL DEFAULT '170141183460469231731687303715884105727',
c_float FLOAT NULL DEFAULT 3.125,
c_double DOUBLE NULL DEFAULT 2.718281828,
c_decimal DECIMAL(27, 9) NULL DEFAULT '123456789.123456789',
c_decimal_compact DECIMAL(18, 4) NULL DEFAULT '99999.1234',
c_pi DOUBLE NULL DEFAULT PI,
c_e DOUBLE NULL DEFAULT E,
c_char CHAR(8) NULL DEFAULT 'charDemo',
c_varchar VARCHAR(32) NULL DEFAULT '',
c_string STRING NULL DEFAULT 'plain string',
c_datetime DATETIME NULL DEFAULT '2025-10-25 11:22:33',
c_date DATE NULL DEFAULT '2025-10-31',
c_json JSON NULL,
c_ipv4 IPV4 NULL DEFAULT '192.168.1.1',
c_ipv6 IPV6 NULL DEFAULT '2001:db8::1',
c_array_int ARRAY<INT> NULL DEFAULT '[]',
c_array_string ARRAY<STRING> NULL,
c_map_str_int MAP<STRING, INT> NULL,
c_struct STRUCT<f1:INT,f2:STRING,f3:BOOLEAN> NULL,
c_variant VARIANT NULL
) PROPERTIES ( 'replication_num' = '1');

-- INSERT statements omitted in the example
SELECT
DEFAULT(c_bool),
DEFAULT(c_tinyint),
DEFAULT(c_smallint),
DEFAULT(c_int),
DEFAULT(c_bigint),
DEFAULT(c_largeint),
DEFAULT(c_float),
DEFAULT(c_double),
DEFAULT(c_decimal),
DEFAULT(c_decimal_compact),
DEFAULT(c_pi),
DEFAULT(c_e),
DEFAULT(c_char),
DEFAULT(c_varchar),
DEFAULT(c_string),
DEFAULT(c_datetime),
DEFAULT(c_date),
DEFAULT(c_json),
DEFAULT(c_ipv4),
DEFAULT(c_ipv6),
DEFAULT(c_array_int),
DEFAULT(c_array_string),
DEFAULT(c_map_str_int),
DEFAULT(c_struct),
DEFAULT(c_variant)
FROM test_default_scalar
LIMIT 1;
```
```text
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
| DEFAULT(c_bool) | DEFAULT(c_tinyint) | DEFAULT(c_smallint) | DEFAULT(c_int) | DEFAULT(c_bigint) | DEFAULT(c_largeint) | DEFAULT(c_float) | DEFAULT(c_double) | DEFAULT(c_decimal) | DEFAULT(c_decimal_compact) | DEFAULT(c_pi) | DEFAULT(c_e) | DEFAULT(c_char) | DEFAULT(c_varchar) | DEFAULT(c_string) | DEFAULT(c_datetime) | DEFAULT(c_date) | DEFAULT(c_json) | DEFAULT(c_ipv4) | DEFAULT(c_ipv6) | DEFAULT(c_array_int) | DEFAULT(c_array_string) | DEFAULT(c_map_str_int) | DEFAULT(c_struct) | DEFAULT(c_variant) |
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
| 1 | 7 | 32000 | 2147483647 | 9223372036854775807 | 170141183460469231731687303715884105727 | 3.125 | 2.718281828 | 123456789.123456789 | 99999.1234 | 3.141592653589793 | 2.718281828459045 | charDemo | | plain string | 2025-10-25 11:22:33 | 2025-10-31 | NULL | 192.168.1.1 | 2001:db8::1 | [] | NULL | NULL | NULL | NULL |
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
```

2. Aggregate type example
```sql
CREATE TABLE test_default_agg (
k_id INT NOT NULL COMMENT '聚合键',
bitmap_col BITMAP BITMAP_UNION,
hll_col HLL HLL_UNION,
quantile_col QUANTILE_STATE QUANTILE_UNION
)AGGREGATE KEY(k_id)
PROPERTIES ( 'replication_num' = '1' );

SELECT
default(bitmap_col),default(hll_col)
FROM test_default_agg
LIMIT 1;
-- ERROR 1105 (HY000): errCode = 2, detailMessage = (127.0.0.1)[INVALID_ARGUMENT]Agg type(HLL, BITMAP, QUANTILE_STATE) cannot be used for the DEFAULT function
```

3. Non-constant default value (`CURRENT_TIMESTAMP`, `CURRENT_DATE`) example:
```sql
CREATE TABLE test_non_const_default_value_t (
null_dt DATETIME NULL DEFAULT CURRENT_TIMESTAMP,
not_null_dt DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
null_d DATE NULL DEFAULT CURRENT_DATE,
not_null_d DATE NOT NULL DEFAULT CURRENT_DATE
) PROPERTIES ( 'replication_num' = '1' );


SELECT
DEFAULT(null_dt), DEFAULT(not_null_dt),
DEFAULT(null_d), DEFAULT(not_null_d)
FROM test_non_const_default_value_t
LIMIT 1;
```
```text
+------------------+----------------------+-----------------+---------------------+
| DEFAULT(null_dt) | DEFAULT(not_null_dt) | DEFAULT(null_d) | DEFAULT(not_null_d) |
+------------------+----------------------+-----------------+---------------------+
| NULL | 0000-01-01 00:00:00 | NULL | 0000-01-01 |
+------------------+----------------------+-----------------+---------------------+
```

4. constant value
```sql
SELECT DEFAULT('hello');
-- ERROR 1105 (HY000): errCode = 2, detailMessage = DEFAULT function requires a column reference, not a constant or expression

SELECT DEFAULT(NULL);
-- ERROR 1105 (HY000): errCode = 2, detailMessage = DEFAULT function requires a column reference, not a constant or expression
```
164 changes: 164 additions & 0 deletions ...cs/current/sql-manual/sql-functions/scalar-functions/other-functions/default.md
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---
{
"title": "DEFAULT",
"language": "zh-CN"
}
---

## 描述

返回表中特定列的默认值。如果该列没有默认值，则会抛出错误。

该函数与 MySQL 中的 [DEFAULT 函数](https://dev.mysql.com/doc/refman/8.4/en/miscellaneous-functions.html#function_default) 行为一致

## 语法

```sql
DEFAULT(<column>)
```

## 参数

| 参数 | 说明 |
| ---------- | ---------------------------------------------- |
| `<column>` | 需要查询默认值的列。仅接受列，否则会抛出错误。 |

## 返回值

常量默认值(包括`PI`, `E`)：
- 若有设置默认值，则返回对应的默认值
- 若没有设置默认值，且列不为 NOT NULL， 则返回 NULL
- 若没有设置默认值，且列为 NOT NULL， 则抛出错误

非常量默认值(`CURRENT_TIMESTAMP`, `CURRENT_DATE`):
- 若该列不为 NOT NULL，则返回 NULL
- 若该列为 NOT NULL，则返回对应类型的最小值 `0000-01-01 00:00:00` 或 `0000-01-01`

特殊情况:
- 当输入列为聚合类型时(`HLL`, `BITMAP`, `QUANTILE_STATE`), 抛出错误
- 输入参数仅允许列，当输入为常量(包括 NULL)或表达式时，抛出错误

[Doris 支持的默认值相关参数](https://doris.apache.org/zh-CN/docs/dev/sql-manual/sql-statements/table-and-view/table/CREATE-TABLE#%E5%88%97%E7%9A%84%E9%BB%98%E8%AE%A4%E5%80%BC%E7%9B%B8%E5%85%B3%E5%8F%82%E6%95%B0)

## 举例

1. 非聚合类型常量默认值举例
```sql
-- setup
-- 表中没有显示表明DEFAULT值的代表其默认值仅接受 NULL 值
-- ARRAY 类型的默认值仅接受 `[]` 和 NULL
CREATE TABLE test_default_scalar (
c_bool BOOLEAN NULL DEFAULT 1,
c_tinyint TINYINT NULL DEFAULT 7,
c_smallint SMALLINT NULL DEFAULT 32000,
c_int INT NULL DEFAULT 2147483647,
c_bigint BIGINT NULL DEFAULT 9223372036854775807,
c_largeint LARGEINT NULL DEFAULT '170141183460469231731687303715884105727',
c_float FLOAT NULL DEFAULT 3.125,
c_double DOUBLE NULL DEFAULT 2.718281828,
c_decimal DECIMAL(27, 9) NULL DEFAULT '123456789.123456789',
c_decimal_compact DECIMAL(18, 4) NULL DEFAULT '99999.1234',
c_pi DOUBLE NULL DEFAULT PI,
c_e DOUBLE NULL DEFAULT E,
c_char CHAR(8) NULL DEFAULT 'charDemo',
c_varchar VARCHAR(32) NULL DEFAULT '',
c_string STRING NULL DEFAULT 'plain string',
c_datetime DATETIME NULL DEFAULT '2025-10-25 11:22:33',
c_date DATE NULL DEFAULT '2025-10-31',
c_json JSON NULL,
c_ipv4 IPV4 NULL DEFAULT '192.168.1.1',
c_ipv6 IPV6 NULL DEFAULT '2001:db8::1',
c_array_int ARRAY<INT> NULL DEFAULT '[]',
c_array_string ARRAY<STRING> NULL,
c_map_str_int MAP<STRING, INT> NULL,
c_struct STRUCT<f1:INT,f2:STRING,f3:BOOLEAN> NULL,
c_variant VARIANT NULL
) PROPERTIES ( 'replication_num' = '1');

-- 例中省略 INSERT 语句
SELECT
DEFAULT(c_bool),
DEFAULT(c_tinyint),
DEFAULT(c_smallint),
DEFAULT(c_int),
DEFAULT(c_bigint),
DEFAULT(c_largeint),
DEFAULT(c_float),
DEFAULT(c_double),
DEFAULT(c_decimal),
DEFAULT(c_decimal_compact),
DEFAULT(c_pi),
DEFAULT(c_e),
DEFAULT(c_char),
DEFAULT(c_varchar),
DEFAULT(c_string),
DEFAULT(c_datetime),
DEFAULT(c_date),
DEFAULT(c_json),
DEFAULT(c_ipv4),
DEFAULT(c_ipv6),
DEFAULT(c_array_int),
DEFAULT(c_array_string),
DEFAULT(c_map_str_int),
DEFAULT(c_struct),
DEFAULT(c_variant)
FROM test_default_scalar
LIMIT 1;
```
```text
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
| DEFAULT(c_bool) | DEFAULT(c_tinyint) | DEFAULT(c_smallint) | DEFAULT(c_int) | DEFAULT(c_bigint) | DEFAULT(c_largeint) | DEFAULT(c_float) | DEFAULT(c_double) | DEFAULT(c_decimal) | DEFAULT(c_decimal_compact) | DEFAULT(c_pi) | DEFAULT(c_e) | DEFAULT(c_char) | DEFAULT(c_varchar) | DEFAULT(c_string) | DEFAULT(c_datetime) | DEFAULT(c_date) | DEFAULT(c_json) | DEFAULT(c_ipv4) | DEFAULT(c_ipv6) | DEFAULT(c_array_int) | DEFAULT(c_array_string) | DEFAULT(c_map_str_int) | DEFAULT(c_struct) | DEFAULT(c_variant) |
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
| 1 | 7 | 32000 | 2147483647 | 9223372036854775807 | 170141183460469231731687303715884105727 | 3.125 | 2.718281828 | 123456789.123456789 | 99999.1234 | 3.141592653589793 | 2.718281828459045 | charDemo | | plain string | 2025-10-25 11:22:33 | 2025-10-31 | NULL | 192.168.1.1 | 2001:db8::1 | [] | NULL | NULL | NULL | NULL |
+-----------------+--------------------+---------------------+----------------+---------------------+-----------------------------------------+------------------+-------------------+---------------------+----------------------------+-------------------+-------------------+-----------------+--------------------+-------------------+---------------------+-----------------+-----------------+-----------------+-----------------+----------------------+-------------------------+------------------------+-------------------+--------------------+
```

2. 聚合类型举例
```sql
CREATE TABLE test_default_agg (
k_id INT NOT NULL COMMENT '聚合键',
bitmap_col BITMAP BITMAP_UNION,
hll_col HLL HLL_UNION,
quantile_col QUANTILE_STATE QUANTILE_UNION
)AGGREGATE KEY(k_id)
PROPERTIES ( 'replication_num' = '1' );

SELECT
default(bitmap_col),default(hll_col)
FROM test_default_agg
LIMIT 1;
-- ERROR 1105 (HY000): errCode = 2, detailMessage = (127.0.0.1)[INVALID_ARGUMENT]Agg type(HLL, BITMAP, QUANTILE_STATE) cannot be used for the DEFAULT function
```

3. 非常量默认值(`CURRENT_TIMESTAMP`, `CURRENT_DATE`)举例：
```sql
CREATE TABLE test_non_const_default_value_t (
null_dt DATETIME NULL DEFAULT CURRENT_TIMESTAMP,
not_null_dt DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
null_d DATE NULL DEFAULT CURRENT_DATE,
not_null_d DATE NOT NULL DEFAULT CURRENT_DATE
) PROPERTIES ( 'replication_num' = '1' );


SELECT
DEFAULT(null_dt), DEFAULT(not_null_dt),
DEFAULT(null_d), DEFAULT(not_null_d)
FROM test_non_const_default_value_t
LIMIT 1;
```
```text
+------------------+----------------------+-----------------+---------------------+
| DEFAULT(null_dt) | DEFAULT(not_null_dt) | DEFAULT(null_d) | DEFAULT(not_null_d) |
+------------------+----------------------+-----------------+---------------------+
| NULL | 0000-01-01 00:00:00 | NULL | 0000-01-01 |
+------------------+----------------------+-----------------+---------------------+
```

4. 常量值
```sql
SELECT DEFAULT('hello');
-- ERROR 1105 (HY000): errCode = 2, detailMessage = DEFAULT function requires a column reference, not a constant or expression

SELECT DEFAULT(NULL);
-- ERROR 1105 (HY000): errCode = 2, detailMessage = DEFAULT function requires a column reference, not a constant or expression
```
1 change: 1 addition & 0 deletions sidebars.json
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Expand Up @@ -1763,6 +1763,7 @@
"label": "Other Functions",
"items": [
"sql-manual/sql-functions/scalar-functions/other-functions/convert-to",
"sql-manual/sql-functions/scalar-functions/other-functions/default",
"sql-manual/sql-functions/scalar-functions/other-functions/esquery",
"sql-manual/sql-functions/scalar-functions/other-functions/field",
"sql-manual/sql-functions/scalar-functions/other-functions/g",
Expand Down