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new e4992eae add if in table basic function from 2091 (#1090)
e4992eae is described below
commit e4992eaef5a99429e49cd94e1c148d6ed5e7ba1a
Author: leto-b <[email protected]>
AuthorDate: Thu Apr 23 17:44:56 2026 +0800
add if in table basic function from 2091 (#1090)
---
.../Table/SQL-Manual/Basis-Function_apache.md | 44 +++++++++++++++++++
.../Table/SQL-Manual/Basis-Function_timecho.md | 45 ++++++++++++++++++++
.../SQL-Manual/Basis-Function_apache.md | 44 +++++++++++++++++++
.../SQL-Manual/Basis-Function_timecho.md | 45 ++++++++++++++++++++
.../Table/SQL-Manual/Basis-Function_apache.md | 49 +++++++++++++++++++++-
.../Table/SQL-Manual/Basis-Function_timecho.md | 49 ++++++++++++++++++++++
.../SQL-Manual/Basis-Function_apache.md | 47 +++++++++++++++++++++
.../SQL-Manual/Basis-Function_timecho.md | 49 ++++++++++++++++++++++
8 files changed, 371 insertions(+), 1 deletion(-)
diff --git a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
index 575551b3..96564dbc 100644
--- a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
+++ b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
@@ -1286,6 +1286,50 @@ Returns the first non-null value from the given list of
parameters.
coalesce(value1, value2[, ...])
```
+### 7.3 IF Expression
+The IF expression has two forms: one that specifies only the true value, and
another that specifies both the true value and the false value.
+
+| Form | Description
| Output Type Restrictions |
+| ---------------------------------------------- |
------------------------------------------------------------------------------------------------------------------------------------
| ------------------------ |
+| `IF(condition, true_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `null` is returned and
`true_value` is not evaluated. | — |
+| `IF(condition, true_value, false_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `false_value` is
computed and returned. | The data types of `true_value` and `false_value`
**must be exactly the same**. Implicit type conversion is not supported. |
+
+> Supported since V2.0.9-beta
+
+**Examples:**
+
+1. Equivalent examples of IF and CASE expressions:
+```SQL
+-- IF syntax
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- Equivalent CASE syntax
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. Output type restriction examples:
+```SQL
+-- Succeeds
+-- temperature (float) and humidity (float) have matching types
+SELECT IF(temperature > 85, temperature, humidity) FROM table1;
+
+-- Fails
+-- temperature (float) and status (boolean) have mismatched types
+SELECT IF(temperature > 85, temperature, status) FROM table1;
+```
+
+
## 8. Conversion Functions
### 8.1 Conversion Functions
diff --git a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
index 7f354dc8..caf0988b 100644
--- a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
+++ b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
@@ -1287,6 +1287,51 @@ Returns the first non-null value from the given list of
parameters.
coalesce(value1, value2[, ...])
```
+### 7.3 IF Expression
+
+The IF expression has two forms: one that specifies only the true value, and
another that specifies both the true value and the false value.
+
+| Form | Description
| Output Type Restrictions |
+| ---------------------------------------------- |
------------------------------------------------------------------------------------------------------------------------------------
| ------------------------ |
+| `IF(condition, true_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `null` is returned and
`true_value` is not evaluated. | — |
+| `IF(condition, true_value, false_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `false_value` is
computed and returned. | The data types of `true_value` and `false_value`
**must be exactly the same**. Implicit type conversion is not supported. |
+
+> Supported since V2.0.9.1
+
+**Examples:**
+
+1. Equivalent examples of IF and CASE expressions:
+```SQL
+-- IF syntax
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- Equivalent CASE syntax
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. Output type restriction examples:
+```SQL
+-- Succeeds
+-- temperature (float) and humidity (float) have matching types
+SELECT IF(temperature > 85, temperature, humidity) FROM table1;
+
+-- Fails
+-- temperature (float) and status (boolean) have mismatched types
+SELECT IF(temperature > 85, temperature, status) FROM table1;
+```
+
+
## 8. Conversion Functions
### 8.1 Conversion Functions
diff --git a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
index 575551b3..96564dbc 100644
--- a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
+++ b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
@@ -1286,6 +1286,50 @@ Returns the first non-null value from the given list of
parameters.
coalesce(value1, value2[, ...])
```
+### 7.3 IF Expression
+The IF expression has two forms: one that specifies only the true value, and
another that specifies both the true value and the false value.
+
+| Form | Description
| Output Type Restrictions |
+| ---------------------------------------------- |
------------------------------------------------------------------------------------------------------------------------------------
| ------------------------ |
+| `IF(condition, true_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `null` is returned and
`true_value` is not evaluated. | — |
+| `IF(condition, true_value, false_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `false_value` is
computed and returned. | The data types of `true_value` and `false_value`
**must be exactly the same**. Implicit type conversion is not supported. |
+
+> Supported since V2.0.9-beta
+
+**Examples:**
+
+1. Equivalent examples of IF and CASE expressions:
+```SQL
+-- IF syntax
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- Equivalent CASE syntax
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. Output type restriction examples:
+```SQL
+-- Succeeds
+-- temperature (float) and humidity (float) have matching types
+SELECT IF(temperature > 85, temperature, humidity) FROM table1;
+
+-- Fails
+-- temperature (float) and status (boolean) have mismatched types
+SELECT IF(temperature > 85, temperature, status) FROM table1;
+```
+
+
## 8. Conversion Functions
### 8.1 Conversion Functions
diff --git a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
index 7f354dc8..caf0988b 100644
--- a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
+++ b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
@@ -1287,6 +1287,51 @@ Returns the first non-null value from the given list of
parameters.
coalesce(value1, value2[, ...])
```
+### 7.3 IF Expression
+
+The IF expression has two forms: one that specifies only the true value, and
another that specifies both the true value and the false value.
+
+| Form | Description
| Output Type Restrictions |
+| ---------------------------------------------- |
------------------------------------------------------------------------------------------------------------------------------------
| ------------------------ |
+| `IF(condition, true_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `null` is returned and
`true_value` is not evaluated. | — |
+| `IF(condition, true_value, false_value)` | If the condition evaluates to
true, `true_value` is computed and returned; otherwise, `false_value` is
computed and returned. | The data types of `true_value` and `false_value`
**must be exactly the same**. Implicit type conversion is not supported. |
+
+> Supported since V2.0.9.1
+
+**Examples:**
+
+1. Equivalent examples of IF and CASE expressions:
+```SQL
+-- IF syntax
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- Equivalent CASE syntax
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. Output type restriction examples:
+```SQL
+-- Succeeds
+-- temperature (float) and humidity (float) have matching types
+SELECT IF(temperature > 85, temperature, humidity) FROM table1;
+
+-- Fails
+-- temperature (float) and status (boolean) have mismatched types
+SELECT IF(temperature > 85, temperature, status) FROM table1;
+```
+
+
## 8. Conversion Functions
### 8.1 Conversion Functions
diff --git a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
index 78febd1b..cacb56d9 100644
--- a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
+++ b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_apache.md
@@ -1265,6 +1265,53 @@ SELECT a, b,
coalesce(value1, value2[, ...])
```
+### 7.3 IF 表达式
+
+IF 表达式有两种形式：一种仅指定真值（true\_value），另一种同时指定真值和假值（false\_value）。
+
+| 形式 | 说明
|
输出类型限制
|
+| ---------------------------------------------- |
-----------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------
|
+| `if(condition, true_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则返回`null`，且`true_value`不会被计算。 |
|
+| `if(condition, true_value, false_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则计算并返回`false_value`。 |
`true_value`和`false_value`的数据类型**必须完全一致**，不支持隐式类型转换。 |
+
+> V 2.0.9-beta 版本起支持
+
+**示例：**
+
+1. IF 表达式和 CASE 表达式等价示例：
+
+```SQL
+-- IF 写法
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- CASE 等价写法
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. 输出类型限制示例：
+
+```SQL
+-- 成功
+-- temperature（float) 和 humidity（float） 类型一致
+select if(temperature > 85, temperature, humidity) from table1
+
+-- 失败
+-- temperature(float) 和 status(boolean) 类型不一致
+select if(temperature > 85, temperature, status) from table1
+```
+
+
## 8. 转换函数
### 8.1 转换函数
@@ -1272,7 +1319,7 @@ coalesce(value1, value2[, ...])
#### 8.1.1 cast(value AS type) → type
1. 显式地将一个值转换为指定类型。
-2. 可以用于将字符串（varchar）转换为数值类型，或数值转换为字符串类型。
+2. 可以用于将字符串（varchar）转换为数值类型，或数值转换为字符串类型
3. 如果转换失败，将抛出运行时错误。
示例：
diff --git a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
index 210eb261..160e96a3 100644
--- a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
+++ b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function_timecho.md
@@ -1265,6 +1265,55 @@ SELECT a, b,
coalesce(value1, value2[, ...])
```
+
+### 7.3 IF 表达式
+
+IF 表达式有两种形式：一种仅指定真值（true\_value），另一种同时指定真值和假值（false\_value）。
+
+| 形式 | 说明
|
输出类型限制
|
+| ---------------------------------------------- |
-----------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------
|
+| `if(condition, true_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则返回`null`，且`true_value`不会被计算。 |
|
+| `if(condition, true_value, false_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则计算并返回`false_value`。 |
`true_value`和`false_value`的数据类型**必须完全一致**，不支持隐式类型转换。 |
+
+> V 2.0.9.1 版本起支持
+
+**示例：**
+
+1. IF 表达式和 CASE 表达式等价示例：
+
+```SQL
+-- IF 写法
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- CASE 等价写法
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. 输出类型限制示例：
+
+```SQL
+-- 成功
+-- temperature（float) 和 humidity（float） 类型一致
+select if(temperature > 85, temperature, humidity) from table1
+
+-- 失败
+-- temperature(float) 和 status(boolean) 类型不一致
+select if(temperature > 85, temperature, status) from table1
+```
+
+
+
## 8. 转换函数
### 8.1 转换函数
diff --git a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
index b1c772aa..bcb814cf 100644
--- a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
+++ b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_apache.md
@@ -1265,6 +1265,53 @@ SELECT a, b,
coalesce(value1, value2[, ...])
```
+### 7.3 IF 表达式
+
+IF 表达式有两种形式：一种仅指定真值（true\_value），另一种同时指定真值和假值（false\_value）。
+
+| 形式 | 说明
|
输出类型限制
|
+| ---------------------------------------------- |
-----------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------
|
+| `if(condition, true_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则返回`null`，且`true_value`不会被计算。 |
|
+| `if(condition, true_value, false_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则计算并返回`false_value`。 |
`true_value`和`false_value`的数据类型**必须完全一致**，不支持隐式类型转换。 |
+
+> V2.0.9-beta 版本起支持
+
+**示例：**
+
+1. IF 表达式和 CASE 表达式等价示例：
+
+```SQL
+-- IF 写法
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- CASE 等价写法
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. 输出类型限制示例：
+
+```SQL
+-- 成功
+-- temperature（float) 和 humidity（float） 类型一致
+select if(temperature > 85, temperature, humidity) from table1
+
+-- 失败
+-- temperature(float) 和 status(boolean) 类型不一致
+select if(temperature > 85, temperature, status) from table1
+```
+
+
## 8. 转换函数
### 8.1 转换函数
diff --git a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
index 210eb261..160e96a3 100644
--- a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
+++ b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function_timecho.md
@@ -1265,6 +1265,55 @@ SELECT a, b,
coalesce(value1, value2[, ...])
```
+
+### 7.3 IF 表达式
+
+IF 表达式有两种形式：一种仅指定真值（true\_value），另一种同时指定真值和假值（false\_value）。
+
+| 形式 | 说明
|
输出类型限制
|
+| ---------------------------------------------- |
-----------------------------------------------------------------------------------------------------------
|
-----------------------------------------------------------------------------------------------
|
+| `if(condition, true_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则返回`null`，且`true_value`不会被计算。 |
|
+| `if(condition, true_value, false_value)` |
若条件（condition）为真，则计算并返回`true_value`；否则计算并返回`false_value`。 |
`true_value`和`false_value`的数据类型**必须完全一致**，不支持隐式类型转换。 |
+
+> V 2.0.9.1 版本起支持
+
+**示例：**
+
+1. IF 表达式和 CASE 表达式等价示例：
+
+```SQL
+-- IF 写法
+SELECT
+ device_id,
+ temperature,
+ IF(temperature > 85, 'High Value', 'Low Value')
+FROM table1;
+
+-- CASE 等价写法
+SELECT
+ device_id,
+ temperature,
+ CASE
+ WHEN temperature > 85 THEN 'High Value'
+ ELSE 'Low Value'
+ END
+FROM table1;
+```
+
+2. 输出类型限制示例：
+
+```SQL
+-- 成功
+-- temperature（float) 和 humidity（float） 类型一致
+select if(temperature > 85, temperature, humidity) from table1
+
+-- 失败
+-- temperature(float) 和 status(boolean) 类型不一致
+select if(temperature > 85, temperature, status) from table1
+```
+
+
+
## 8. 转换函数
### 8.1 转换函数
