英文:
go programming: sqlite_master returns EOF using sqlite3 package
问题
我正在尝试在创建表后检查表是否存在，但是"SELECT name FROM sqlite_master WHERE type='table' AND name='testtable';"返回空（EOF）。我做错了什么？
Sqlite3包来自http://code.google.com/p/go-sqlite/source/browse/#hg%2Fgo1%2Fsqlite3
Go版本：1.2.1
实际结果：
hello, world
FileExists(dbname)返回：false
数据库正常
创建testtable...
成功！
插入一些内容...
检查testtable...
扫描变量失败，错误：EOF
期望结果：
hello, world
FileExists(dbname)返回：false
数据库正常
创建testtable...
成功！
插入一些内容...
检查testtable...
检测到表
代码：
package main
import "os"
import "fmt"
import "time"
import "code.google.com/p/go-sqlite/go1/sqlite3"
func main() {
dbname := "sqlite.db"
defer time.Sleep(5000 * time.Millisecond)
fmt.Printf("hello, world\n")
os.Remove(dbname)
fe := FileExists(dbname)
fmt.Printf("FileExists(dbname)返回：%t\n", fe)
db, err := sqlite3.Open(dbname)
defer db.Close()
if err != nil {
fmt.Printf("无法打开数据库，错误：" + err.Error() + "\n")
return
}
fmt.Printf("数据库正常\n")
if fe != true {
fmt.Printf("创建testtable...\n")
err = db.Exec("CREATE TABLE testtable (id INTEGER PRIMARY KEY AUTOINCREMENT, text VARCHAR(200));")
if err != nil {
fmt.Printf("错误：" + err.Error() + "\n")
return
} else {
fmt.Printf("成功！\n")
}
fmt.Printf("插入一些内容...\n")
insertSql := `INSERT INTO testtable(text) VALUES("This is some random text to test it");`
err = db.Exec(insertSql)
if err != nil {
fmt.Printf("插入时出错：" + err.Error() + "\n")
return
}
fmt.Printf("检查testtable...\n")
CheckTable, err := db.Prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='testtable';")
err = CheckTable.Exec()
if err != nil {
fmt.Printf("无法检查表，错误：" + err.Error() + "\n")
return
}
var tablename string
//移除'//'获得相同结果
//requeststatus := CheckTable.Next()
err = CheckTable.Scan(&tablename)
if err != nil {
fmt.Printf("扫描变量失败，错误：" + err.Error() + "\n")
return
}
if tablename != "testtable" {
fmt.Printf("未检测到表\n")
} else {
fmt.Printf("检测到表\n")
}
}
}
func FileExists(fn string) bool {
if _, err := os.Stat(fn); err == nil {
return true
} else {
return false
}
}
英文:
I am trying to check if table exists after table creation but "SELECT name FROM sqlite_master WHERE type='table' AND name='testtable';" returns nothing (EOF). What I am doing wrong?
Sqlite3 package is taken from <http://code.google.com/p/go-sqlite/source/browse/#hg%2Fgo1%2Fsqlite3>
Go version: 1.2.1
Got:
hello, world
FileExists(dbname) returned: false
database ok
creating testtable...
success!
inserting something...
checking testtable...
Failed to scan variable, error: EOF
Expected:
hello, world
FileExists(dbname) returned: false
database ok
creating testtable...
success!
inserting something...
checking testtable...
Table detected
Code:
package main
import "os"
import "fmt"
import "time"
import "code.google.com/p/go-sqlite/go1/sqlite3"
func main() {
dbname := "sqlite.db"
defer time.Sleep(5000 * time.Millisecond)
fmt.Printf("hello, world\n")
os.Remove(dbname)
fe := FileExists(dbname)
fmt.Printf("FileExists(dbname) returned: %t\n", fe)
db, err := sqlite3.Open(dbname)
defer db.Close()
if err != nil {
fmt.Printf("failed to open database, error: " + err.Error() + "\n")
return
}
fmt.Printf("database ok\n")
if fe != true {
fmt.Printf("creating testtable...\n")
err = db.Exec("CREATE TABLE testtable (id INTEGER PRIMARY KEY AUTOINCREMENT, text VARCHAR(200));")
if err != nil {
fmt.Printf("error: " + err.Error() + "\n")
return
} else {
fmt.Printf("success!\n")
}
fmt.Printf("inserting something...\n")
insertSql := `INSERT INTO testtable(text) VALUES("This is some random text to test it");`
err = db.Exec(insertSql)
if err != nil {
fmt.Printf("Error while Inserting: " + err.Error() + "\n")
return
}
fmt.Printf("checking testtable...\n")
CheckTable, err := db.Prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='testtable';")
err = CheckTable.Exec()
if err != nil {
fmt.Printf("failed to check table, error: " + err.Error() + "\n")
return
}
var tablename string
//Same result removing '//'
//requeststatus := CheckTable.Next()
err = CheckTable.Scan(&tablename)
if err != nil {
fmt.Printf("Failed to scan variable, error: " + err.Error() + "\n")
return
}
if tablename != "testtable" {
fmt.Printf("No table detected\n")
} else {
fmt.Printf("Table detected\n")
}
}
}
func FileExists(fn string) bool {
if _, err := os.Stat(fn); err == nil {
return true
} else {
return false
}
}
答案1
得分: 1
Stmt.Exec文档中写道：
> 不返回任何行。
要返回数据，请改用Query。
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