kotlin sql查字段长度

在 Kotlin 中，您可以使用以下代码来查询 SQL 表中的字段长度：

import java.sql.Connection
import java.sql.DriverManager
import java.sql.SQLException

fun main() {
    // 建立数据库连接
    val url = "jdbc:mysql://localhost:3306/database_name"
    val username = "your_username"
    val password = "your_password"

    try {
        val connection: Connection = DriverManager.getConnection(url, username, password)
        
        // 查询字段长度
        val columnName = "column_name"
        val tableName = "table_name"
        val query = "SELECT CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = ? AND COLUMN_NAME = ?"
        
        val statement = connection.prepareStatement(query)
        statement.setString(1, tableName)
        statement.setString(2, columnName)

        val resultSet = statement.executeQuery()
        
        if (resultSet.next()) {
            val maxLength = resultSet.getInt(1)
            println("Max length of $columnName in $tableName is $maxLength")
        } else {
            println("Column $columnName not found in table $tableName")
        }
        
        // 关闭连接
        resultSet.close()
        statement.close()
        connection.close()
    } catch (e: SQLException) {
        e.printStackTrace()
    }
}

请注意替换代码中的 `database_name`、`your_username`、`your_password`、`column_name` 和 `table_name` 为您实际使用的值。