docs: Fix Enumeration topic examples

- Switch manual create with plain SQL to mock an already existing table
- Add insert function to test that Exposed table object successfully works with
database object not created by Exposed
- Move these existing enum column functions to runH2Examples()
- Fix detekt issues in changed files

documentation-website/Writerside/snippets/exposed-data-types/src/main/kotlin/org/example/App.kt

@@ -2,8 +2,8 @@ package org.example
 
 import org.example.examples.EnumerationExamples
 import org.example.examples.JSONandJSONBExamples
-import org.example.examples.TeamsTable
 import org.example.examples.TeamProjectsTable
+import org.example.examples.TeamsTable
 import org.jetbrains.exposed.sql.Database
 import org.jetbrains.exposed.sql.DatabaseConfig
 import org.jetbrains.exposed.sql.SchemaUtils
@@ -36,7 +36,6 @@ fun runMySQLExamples() {
         jsonExamples.useContains()
         jsonExamples.useContainsWithPath()
         jsonArraysExamples()
-        enumExamples.createTableWithExistingEnumColumn()
     }
 }
 
@@ -53,6 +52,8 @@ fun runH2Examples() {
         jsonExamples.example()
         jsonExamples.useExtract()
         jsonExamples.useExists()
+        enumExamples.createTableWithExistingEnumColumn()
+        enumExamples.insertEnumIntoTableWithExistingEnumColumn()
     }
 }
 
@@ -79,4 +80,3 @@ fun jsonArraysExamples() {
     SchemaUtils.create(TeamProjectsTable)
     jsonExamples.insertJSONArrays()
 }
-

documentation-website/Writerside/snippets/exposed-data-types/src/main/kotlin/org/example/examples/EnumerationExamples.kt

@@ -2,6 +2,7 @@ package org.example.examples
 
 import org.jetbrains.exposed.sql.SchemaUtils
 import org.jetbrains.exposed.sql.Table
+import org.jetbrains.exposed.sql.insert
 import org.jetbrains.exposed.sql.transactions.transaction
 import org.postgresql.util.PGobject
 
@@ -15,21 +16,40 @@ class PGEnum<T : Enum<T>>(enumTypeName: String, enumValue: T?) : PGobject() {
 }
 
 object EnumTable : Table() {
-    val enumColumn = customEnumeration("enumColumn", "FooEnum", { value -> Foo.valueOf(value as String) }, { PGEnum("FooEnum", it) })
+    val enumColumn: Column<Foo> = customEnumeration(
+        name = "enumColumn",
+        sql = "FooEnum",
+        fromDb = { value -> Foo.valueOf(value as String) },
+        toDb = { PGEnum("FooEnum", it) }
+    )
 }
 
 object NewEnumTable : Table() {
-    val newEnumColumn = customEnumeration("enumColumn", "ENUM('BAR', 'BAZ')", { value -> Foo.valueOf(value as String) }, { it.name })
+    val newEnumColumn: Column<Foo> = customEnumeration(
+        name = "enumColumn",
+        sql = "ENUM('BAR', 'BAZ')",
+        fromDb = { value -> Foo.valueOf(value as String) },
+        toDb = { it.name }
+    )
 }
 
 object ExistingEnumTable : Table() {
-    val existingEnumColumn = customEnumeration("enumColumn", { value -> Foo.valueOf(value as String) }, { it.name })
+    val existingEnumColumn: Column<Foo> = customEnumeration(
+        name = "enumColumn",
+        fromDb = { value -> Foo.valueOf(value as String) },
+        toDb = { it.name }
+    )
 }
 
 class EnumerationExamples {
     fun createTableWithExistingEnumColumn() {
         transaction {
-            SchemaUtils.create(MySQLEnumTable)
+            exec("""CREATE TABLE IF NOT EXISTS EXISTINGENUM ("enumColumn" ENUM('BAR', 'BAZ') NOT NULL)""")
+        }
+    }
+    fun insertEnumIntoTableWithExistingEnumColumn() {
+        ExistingEnumTable.insert {
+            it[existingEnumColumn] = Foo.BAZ
         }
     }
     fun createTableWithEnumColumn() {