A modern programming language that makes developers happier.

kotlinlang

I want to build a query string  with coolest way
```val query = "INSERT INTO table (id, name, age) VALUES (?,?,?)"```
this is ordinary way (i usually use) and the problem is, the parameter `?`need to append according to the increase or decrease of column `id, name, age`

so i tried,,,
```var column = "id, name, age"
val query = "INSERT INTO table (${column}) VALUES (${(1..3).forEach { ? }})" ```
the part `${(1..3).forEach { ? }}`  is incorrect, i don’t know how to do.
hope you got me,

```val columns = listOf("id", "name", "age")
println("INSERT INTO table (${columns.joinToString(", ")}) VALUES (${columns.map{ "?" }.joinToString(", ")})")```
I think you're better off using some framework to create typesafe queries etc. though

You technically don't need a separate may call
`columns.joinToString(", ") { "?" }`

This is a nice excercise, but I would advise to use a library (even JDBC) for security reasons, to prevent SQL injection attacks.
For example: <https://github.com/JetBrains/Exposed>

Theres no particular reason to use a library, as long as its ? you are adding. But also maybe don't need to build sql in coolest way, just simplest. If there are only 2 variants, could just type them in.....

After many years of working with SQL in different languages, I would advise to stay away from manual query composition and let a robust lib do the job. If this is just for a personal project, to learn and experiment, then fine go for it.

```fun &lt;T&gt; Iterable&lt;T&gt;.joinToSQLIn(separator: CharSequence = ",", prefix: CharSequence = "(", postfix: CharSequence = ")", limit: Int = -1, transform: ((T) -&gt; CharSequence)? = { _ -&gt; "?"}): String
        = this.joinToString(separator = separator, prefix = prefix, postfix = postfix, limit = limit, transform = transform)```
then:
`SELECT ${cols.joinToSQLIn()} ...`

thank you all,,,,and thanks for the advice using sql framework

I tried Exposed and I was not a fan of it. I would suggest using another lib. Like kwery , kuery, ktorm

<https://zsoltherpai.github.io/fluent-jdbc/> is great