From 1253eafad5a1a9397b1d9e618444adecc06e4689 Mon Sep 17 00:00:00 2001 From: Leto_b Date: Wed, 22 Apr 2026 15:55:01 +0800 Subject: [PATCH] add if in table basic function from 2091 --- .../Table/SQL-Manual/Basis-Function_apache.md | 44 +++++++++++++++++ .../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 ++++++++++++++++++- .../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 575551b3b..96564dbcd 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 7f354dc89..caf0988b5 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 575551b3b..96564dbcd 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 7f354dc89..caf0988b5 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 78febd1b0..cacb56d9c 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 210eb2613..160e96a39 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 b1c772aac..bcb814cf2 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 210eb2613..160e96a39 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