[WIP] Add if function into ktorm-support-mysql #163
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@vincentlauvlwj Hi, I try to add sum and sumIf function in ktorm-support-mysql. |
ktorm-support-mysql/src/main/kotlin/me/liuwj/ktorm/support/mysql/Functions.kt
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ktorm-support-mysql/src/main/kotlin/me/liuwj/ktorm/support/mysql/Functions.kt
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| condition: ColumnDeclaring<Boolean>, | ||
| then: ColumnDeclaring<T>, | ||
| otherwise: ColumnDeclaring<T> |
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Please follow the existing code style, fix the indent.
| functionName = "if", | ||
| arguments = listOf(condition, then, otherwise).map { it.asExpression() }, | ||
| sqlType = then.sqlType |
| sum(IF((Employees.salary greaterEq 100L).cast(BooleanSqlType), | ||
| then = ArgumentExpression(1, IntSqlType), | ||
| otherwise = ArgumentExpression(0, IntSqlType))) |
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We can have a overloaded version for Int, fun IF(condition: ColumnDeclaring<Boolean>, then: Int, otherwise: Int), then we don't have to wrap the arguments as ArgumentExpression manually.
Also, overloaded versions for frequent-used types are neccesary, like Int, Long, Double, String, etc.
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@vincentlauvlwj FYI, in this point, at first I created IF function (uppercase).
However, 'detekt' gave me error because of restriction that function name should be started with lower cases.
So, I changed IF to if, and use back-quote.
ktorm-support-mysql/src/test/kotlin/me/liuwj/ktorm/support/mysql/MySqlTest.kt
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* without annotation, error occurred "have the same JVM signature" https://stackoverflow.com/a/51581951/2565527
Whats' this PR do ?
Add sum dsl functions into ktorm-support-mysql
sumIf: generatesum( if(column condition, ifTrue, ifFalse) )sum: generatesum( column condition )In MySQL,
sum( boolean )works as conditional sumBoolean type in MySQL is represented as INT 0 and 1, just like in C.use-case
@Test fun testSumIf() { val countRich = database.from(Employees) .select(sumIf(Employees.salary greaterEq 100L, 1, 0)) .map { row -> row.getInt(1) } assert(countRich.size == 1) assert(countRich.first() == 3) } @Test fun testSum() { val countRich = database.from(Employees) .select(sum(Employees.salary greaterEq 100L)) .map { row -> row.getInt(1) } assert(countRich.size == 1) assert(countRich.first() == 3) }