mysql datediff function

Author: vincentlauvlwj

build.gradle

@@ -11,7 +11,7 @@ buildscript {
 
 allprojects {
     group = "me.liuwj.ktorm"
-    version = "2.0"
+    version = "2.1"
 }
 
 subprojects { project ->

hexo-docs/source/en/dialects-and-native-sql.md

@@ -95,7 +95,7 @@ Here is a list of features provided by module ktorm-support-mysql:
 - Add `naturalJoin` function for natural joining, based on `natural join` keyword. 
 - Add `jsonContains` function to determine if the specific item exists in a json array, based on the `json_contains` function in MySQL. 
 - Add `jsonExtract` function to obtain fields in a json, that's the `->` grammar in MySQL, based on `json_extract` function. 
-- Add other functions such as `rand`, `ifnull`, `greatest`, `least`, etc, supporting the corresponding functions in MySQL. 
+- Add other functions such as `rand`, `ifnull`, `greatest`, `least`, `dateDiff`, etc, supporting the corresponding functions in MySQL. 
 
 The features of ktorm-support-postgresql are listed below: 
 

hexo-docs/source/zh-cn/dialects-and-native-sql.md

@@ -95,7 +95,7 @@ on duplicate key update t_employee.salary = t_employee.salary + ?
 - 增加了 `naturalJoin` 函数，支持自然连接，基于 `natural join` 关键字
 - 增加了 `jsonContains` 函数，判断 json 数组中是否存在指定元素，基于 `json_contains` 函数
 - 增加了 `jsonExtract` 函数，支持从 json 中获取字段，即 MySQL 中的 -> 语法，基于 `json_extract` 函数
-- 增加了 `rand`、`ifnull`、`greatest`、`least` 等函数，支持 MySQL 中的同名函数
+- 增加了 `rand`、`ifnull`、`greatest`、`least`、`dateDiff` 等函数，支持 MySQL 中的同名函数
 
 ktorm-support-postgresql 提供的功能有：
 

ktorm-support-mysql/src/main/kotlin/me/liuwj/ktorm/support/mysql/Functions.kt

@@ -3,6 +3,7 @@ package me.liuwj.ktorm.support.mysql
 import me.liuwj.ktorm.expression.ArgumentExpression
 import me.liuwj.ktorm.expression.FunctionExpression
 import me.liuwj.ktorm.schema.*
+import java.time.LocalDate
 
 fun <T : Any> Column<List<T>>.jsonContains(item: T, itemSqlType: SqlType<T>): FunctionExpression<Boolean> {
     val listSqlType = this.sqlType
@@ -101,4 +102,21 @@ fun <T : Any> ColumnDeclaring<T>.ifNull(right: ColumnDeclaring<T>): FunctionExpr
 
 fun <T : Any> ColumnDeclaring<T>.ifNull(right: T?): FunctionExpression<T> {
     return this.ifNull(wrapArgument(right))
+}
+
+fun dateDiff(left: ColumnDeclaring<LocalDate>, right: ColumnDeclaring<LocalDate>): FunctionExpression<Int> {
+    // datediff(left, right)
+    return FunctionExpression(
+        functionName = "datediff",
+        arguments = listOf(left.asExpression(), right.asExpression()),
+        sqlType = IntSqlType
+    )
+}
+
+fun dateDiff(left: ColumnDeclaring<LocalDate>, right: LocalDate): FunctionExpression<Int> {
+    return dateDiff(left, left.wrapArgument(right))
+}
+
+fun dateDiff(left: LocalDate, right: ColumnDeclaring<LocalDate>): FunctionExpression<Int> {
+    return dateDiff(right.wrapArgument(left), right)
 }

ktorm-support-mysql/src/test/kotlin/me/liuwj/ktorm/support/mysql/MySqlTest.kt

@@ -5,9 +5,6 @@ import me.liuwj.ktorm.database.Database
 import me.liuwj.ktorm.database.useConnection
 import me.liuwj.ktorm.dsl.*
 import me.liuwj.ktorm.entity.*
-import me.liuwj.ktorm.expression.FunctionExpression
-import me.liuwj.ktorm.schema.ColumnDeclaring
-import me.liuwj.ktorm.schema.IntSqlType
 import org.junit.Test
 import java.time.LocalDate
 
@@ -183,13 +180,6 @@ class MySqlTest : BaseTest() {
 
     @Test
     fun testMapColumns3() {
-        // MySQL datediff function
-        fun dateDiff(left: LocalDate, right: ColumnDeclaring<LocalDate>) = FunctionExpression(
-            functionName = "datediff",
-            arguments = listOf(right.wrapArgument(left), right.asExpression()),
-            sqlType = IntSqlType
-        )
-
         Employees
             .asSequence()
             .filter { it.departmentId eq 1 }