Ios 如何在sqlite中升级数据库版本并在swift中的表中添加新列
我已经为我的应用程序创建了sqlite表,但现在我想在表中向数据库添加一个新列。ALTERTABLE将帮助我解决这个问题,但首先我想检查数据库版本。 我正在使用PRAGMA user\u version检查用户版本并更新用户版本,但它始终将用户版本返回为0Ios 如何在sqlite中升级数据库版本并在swift中的表中添加新列,ios,swift,sqlite,Ios,Swift,Sqlite,我已经为我的应用程序创建了sqlite表,但现在我想在表中向数据库添加一个新列。ALTERTABLE将帮助我解决这个问题,但首先我想检查数据库版本。 我正在使用PRAGMA user\u version检查用户版本并更新用户版本,但它始终将用户版本返回为0 var database: FMDatabase? = nil class func getInstance() -> ModelManager{ if(sharedInstance.database == n
var database: FMDatabase? = nil
class func getInstance() -> ModelManager{
if(sharedInstance.database == nil){
sharedInstance.database = FMDatabase(path: Util.getPath("XXXX.sqlite"))
}
return sharedInstance
}
func userVersion(){
sharedInstance.database!.open()
var userVer = Int()
let resultSet = sharedInstance.database?.executeQuery("pragma user_version", withArgumentsInArray: nil)
userVer = Int(resultSet!.intForColumn("user_version"))
print("user version : ",userVer)
sharedInstance.database!.close()
}
func updateUserVersion(){
sharedInstance.database!.open()
sharedInstance.database?.executeUpdate("PRAGMA user_version=1", withArgumentsInArray: nil)
sharedInstance.database!.close()
}
您需要在resultSet上调用next()方法,以便在访问intForColumn之前加载第一行
此外,由于您使用的是FMDB,请看一看:它是SQLite的一个快速包装器,FMDB用户会很熟悉它。但是这次您只需编写
让userVer=Int.fetchOne(db,“pragma user\u version”)
。下面的代码可以与Swift 4配合使用
import UIKit
import FMDB
class DataConnection: NSObject {
static let databaseVersion = 2
static var isDatabaseUpdated = false
static var database: FMDatabase? = nil
class func databaseSetup() {
if database == nil {
let docsDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
let dpPath = docsDir.appendingPathComponent("database.sqlite")
let file = FileManager.default
if(!file.fileExists(atPath: dpPath.path)) {
copyDatabase(file: file, dpPath: dpPath)
database = FMDatabase(path: dpPath.path)
do {
database!.open()
try database!.executeUpdate("PRAGMA user_version = \(databaseVersion)", values: nil)
database!.close()
isDatabaseUpdated = true
}catch {
print("Error on updating user_version")
}
}else {
database = FMDatabase(path: dpPath.path)
if !isDatabaseUpdated {
var currentVersion = 0
do {
database!.open()
let resultSet: FMResultSet! = try database!.executeQuery("pragma user_version", values: nil)
while resultSet.next() {
currentVersion = Int(resultSet.int(forColumn: "user_version"))
}
database!.close()
}catch {
print("Error on getting user_version")
}
if databaseVersion > currentVersion {
do {
try file.removeItem(at: dpPath)
}catch {
print("Error on getting user_version")
}
copyDatabase(file: file, dpPath: dpPath)
database = FMDatabase(path: dpPath.path)
do {
database!.open()
try database!.executeUpdate("PRAGMA user_version = \(databaseVersion)", values: nil)
database!.close()
isDatabaseUpdated = true
}catch {
print("Error on updating user_version")
}
}else {
isDatabaseUpdated = true
}
}
}
}
}
private class func copyDatabase(file: FileManager, dpPath: URL){
let dpPathApp = Bundle.main.path(forResource: "database", ofType: "sqlite")
print("resPath: "+String(describing: dpPathApp))
do {
try file.copyItem(atPath: dpPathApp!, toPath: dpPath.path)
print("copyItemAtPath success")
} catch {
print("copyItemAtPath fail")
}
}
}