gitea/vendor/xorm.io/xorm/dialects/oracle.go
2021-07-04 15:10:46 +02:00

874 lines
28 KiB
Go
Vendored

// Copyright 2015 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package dialects
import (
"context"
"errors"
"fmt"
"regexp"
"strconv"
"strings"
"xorm.io/xorm/core"
"xorm.io/xorm/schemas"
)
var (
oracleReservedWords = map[string]bool{
"ACCESS": true,
"ACCOUNT": true,
"ACTIVATE": true,
"ADD": true,
"ADMIN": true,
"ADVISE": true,
"AFTER": true,
"ALL": true,
"ALL_ROWS": true,
"ALLOCATE": true,
"ALTER": true,
"ANALYZE": true,
"AND": true,
"ANY": true,
"ARCHIVE": true,
"ARCHIVELOG": true,
"ARRAY": true,
"AS": true,
"ASC": true,
"AT": true,
"AUDIT": true,
"AUTHENTICATED": true,
"AUTHORIZATION": true,
"AUTOEXTEND": true,
"AUTOMATIC": true,
"BACKUP": true,
"BECOME": true,
"BEFORE": true,
"BEGIN": true,
"BETWEEN": true,
"BFILE": true,
"BITMAP": true,
"BLOB": true,
"BLOCK": true,
"BODY": true,
"BY": true,
"CACHE": true,
"CACHE_INSTANCES": true,
"CANCEL": true,
"CASCADE": true,
"CAST": true,
"CFILE": true,
"CHAINED": true,
"CHANGE": true,
"CHAR": true,
"CHAR_CS": true,
"CHARACTER": true,
"CHECK": true,
"CHECKPOINT": true,
"CHOOSE": true,
"CHUNK": true,
"CLEAR": true,
"CLOB": true,
"CLONE": true,
"CLOSE": true,
"CLOSE_CACHED_OPEN_CURSORS": true,
"CLUSTER": true,
"COALESCE": true,
"COLUMN": true,
"COLUMNS": true,
"COMMENT": true,
"COMMIT": true,
"COMMITTED": true,
"COMPATIBILITY": true,
"COMPILE": true,
"COMPLETE": true,
"COMPOSITE_LIMIT": true,
"COMPRESS": true,
"COMPUTE": true,
"CONNECT": true,
"CONNECT_TIME": true,
"CONSTRAINT": true,
"CONSTRAINTS": true,
"CONTENTS": true,
"CONTINUE": true,
"CONTROLFILE": true,
"CONVERT": true,
"COST": true,
"CPU_PER_CALL": true,
"CPU_PER_SESSION": true,
"CREATE": true,
"CURRENT": true,
"CURRENT_SCHEMA": true,
"CURREN_USER": true,
"CURSOR": true,
"CYCLE": true,
"DANGLING": true,
"DATABASE": true,
"DATAFILE": true,
"DATAFILES": true,
"DATAOBJNO": true,
"DATE": true,
"DBA": true,
"DBHIGH": true,
"DBLOW": true,
"DBMAC": true,
"DEALLOCATE": true,
"DEBUG": true,
"DEC": true,
"DECIMAL": true,
"DECLARE": true,
"DEFAULT": true,
"DEFERRABLE": true,
"DEFERRED": true,
"DEGREE": true,
"DELETE": true,
"DEREF": true,
"DESC": true,
"DIRECTORY": true,
"DISABLE": true,
"DISCONNECT": true,
"DISMOUNT": true,
"DISTINCT": true,
"DISTRIBUTED": true,
"DML": true,
"DOUBLE": true,
"DROP": true,
"DUMP": true,
"EACH": true,
"ELSE": true,
"ENABLE": true,
"END": true,
"ENFORCE": true,
"ENTRY": true,
"ESCAPE": true,
"EXCEPT": true,
"EXCEPTIONS": true,
"EXCHANGE": true,
"EXCLUDING": true,
"EXCLUSIVE": true,
"EXECUTE": true,
"EXISTS": true,
"EXPIRE": true,
"EXPLAIN": true,
"EXTENT": true,
"EXTENTS": true,
"EXTERNALLY": true,
"FAILED_LOGIN_ATTEMPTS": true,
"FALSE": true,
"FAST": true,
"FILE": true,
"FIRST_ROWS": true,
"FLAGGER": true,
"FLOAT": true,
"FLOB": true,
"FLUSH": true,
"FOR": true,
"FORCE": true,
"FOREIGN": true,
"FREELIST": true,
"FREELISTS": true,
"FROM": true,
"FULL": true,
"FUNCTION": true,
"GLOBAL": true,
"GLOBALLY": true,
"GLOBAL_NAME": true,
"GRANT": true,
"GROUP": true,
"GROUPS": true,
"HASH": true,
"HASHKEYS": true,
"HAVING": true,
"HEADER": true,
"HEAP": true,
"IDENTIFIED": true,
"IDGENERATORS": true,
"IDLE_TIME": true,
"IF": true,
"IMMEDIATE": true,
"IN": true,
"INCLUDING": true,
"INCREMENT": true,
"INDEX": true,
"INDEXED": true,
"INDEXES": true,
"INDICATOR": true,
"IND_PARTITION": true,
"INITIAL": true,
"INITIALLY": true,
"INITRANS": true,
"INSERT": true,
"INSTANCE": true,
"INSTANCES": true,
"INSTEAD": true,
"INT": true,
"INTEGER": true,
"INTERMEDIATE": true,
"INTERSECT": true,
"INTO": true,
"IS": true,
"ISOLATION": true,
"ISOLATION_LEVEL": true,
"KEEP": true,
"KEY": true,
"KILL": true,
"LABEL": true,
"LAYER": true,
"LESS": true,
"LEVEL": true,
"LIBRARY": true,
"LIKE": true,
"LIMIT": true,
"LINK": true,
"LIST": true,
"LOB": true,
"LOCAL": true,
"LOCK": true,
"LOCKED": true,
"LOG": true,
"LOGFILE": true,
"LOGGING": true,
"LOGICAL_READS_PER_CALL": true,
"LOGICAL_READS_PER_SESSION": true,
"LONG": true,
"MANAGE": true,
"MASTER": true,
"MAX": true,
"MAXARCHLOGS": true,
"MAXDATAFILES": true,
"MAXEXTENTS": true,
"MAXINSTANCES": true,
"MAXLOGFILES": true,
"MAXLOGHISTORY": true,
"MAXLOGMEMBERS": true,
"MAXSIZE": true,
"MAXTRANS": true,
"MAXVALUE": true,
"MIN": true,
"MEMBER": true,
"MINIMUM": true,
"MINEXTENTS": true,
"MINUS": true,
"MINVALUE": true,
"MLSLABEL": true,
"MLS_LABEL_FORMAT": true,
"MODE": true,
"MODIFY": true,
"MOUNT": true,
"MOVE": true,
"MTS_DISPATCHERS": true,
"MULTISET": true,
"NATIONAL": true,
"NCHAR": true,
"NCHAR_CS": true,
"NCLOB": true,
"NEEDED": true,
"NESTED": true,
"NETWORK": true,
"NEW": true,
"NEXT": true,
"NOARCHIVELOG": true,
"NOAUDIT": true,
"NOCACHE": true,
"NOCOMPRESS": true,
"NOCYCLE": true,
"NOFORCE": true,
"NOLOGGING": true,
"NOMAXVALUE": true,
"NOMINVALUE": true,
"NONE": true,
"NOORDER": true,
"NOOVERRIDE": true,
"NOPARALLEL": true,
"NOREVERSE": true,
"NORMAL": true,
"NOSORT": true,
"NOT": true,
"NOTHING": true,
"NOWAIT": true,
"NULL": true,
"NUMBER": true,
"NUMERIC": true,
"NVARCHAR2": true,
"OBJECT": true,
"OBJNO": true,
"OBJNO_REUSE": true,
"OF": true,
"OFF": true,
"OFFLINE": true,
"OID": true,
"OIDINDEX": true,
"OLD": true,
"ON": true,
"ONLINE": true,
"ONLY": true,
"OPCODE": true,
"OPEN": true,
"OPTIMAL": true,
"OPTIMIZER_GOAL": true,
"OPTION": true,
"OR": true,
"ORDER": true,
"ORGANIZATION": true,
"OSLABEL": true,
"OVERFLOW": true,
"OWN": true,
"PACKAGE": true,
"PARALLEL": true,
"PARTITION": true,
"PASSWORD": true,
"PASSWORD_GRACE_TIME": true,
"PASSWORD_LIFE_TIME": true,
"PASSWORD_LOCK_TIME": true,
"PASSWORD_REUSE_MAX": true,
"PASSWORD_REUSE_TIME": true,
"PASSWORD_VERIFY_FUNCTION": true,
"PCTFREE": true,
"PCTINCREASE": true,
"PCTTHRESHOLD": true,
"PCTUSED": true,
"PCTVERSION": true,
"PERCENT": true,
"PERMANENT": true,
"PLAN": true,
"PLSQL_DEBUG": true,
"POST_TRANSACTION": true,
"PRECISION": true,
"PRESERVE": true,
"PRIMARY": true,
"PRIOR": true,
"PRIVATE": true,
"PRIVATE_SGA": true,
"PRIVILEGE": true,
"PRIVILEGES": true,
"PROCEDURE": true,
"PROFILE": true,
"PUBLIC": true,
"PURGE": true,
"QUEUE": true,
"QUOTA": true,
"RANGE": true,
"RAW": true,
"RBA": true,
"READ": true,
"READUP": true,
"REAL": true,
"REBUILD": true,
"RECOVER": true,
"RECOVERABLE": true,
"RECOVERY": true,
"REF": true,
"REFERENCES": true,
"REFERENCING": true,
"REFRESH": true,
"RENAME": true,
"REPLACE": true,
"RESET": true,
"RESETLOGS": true,
"RESIZE": true,
"RESOURCE": true,
"RESTRICTED": true,
"RETURN": true,
"RETURNING": true,
"REUSE": true,
"REVERSE": true,
"REVOKE": true,
"ROLE": true,
"ROLES": true,
"ROLLBACK": true,
"ROW": true,
"ROWID": true,
"ROWNUM": true,
"ROWS": true,
"RULE": true,
"SAMPLE": true,
"SAVEPOINT": true,
"SB4": true,
"SCAN_INSTANCES": true,
"SCHEMA": true,
"SCN": true,
"SCOPE": true,
"SD_ALL": true,
"SD_INHIBIT": true,
"SD_SHOW": true,
"SEGMENT": true,
"SEG_BLOCK": true,
"SEG_FILE": true,
"SELECT": true,
"SEQUENCE": true,
"SERIALIZABLE": true,
"SESSION": true,
"SESSION_CACHED_CURSORS": true,
"SESSIONS_PER_USER": true,
"SET": true,
"SHARE": true,
"SHARED": true,
"SHARED_POOL": true,
"SHRINK": true,
"SIZE": true,
"SKIP": true,
"SKIP_UNUSABLE_INDEXES": true,
"SMALLINT": true,
"SNAPSHOT": true,
"SOME": true,
"SORT": true,
"SPECIFICATION": true,
"SPLIT": true,
"SQL_TRACE": true,
"STANDBY": true,
"START": true,
"STATEMENT_ID": true,
"STATISTICS": true,
"STOP": true,
"STORAGE": true,
"STORE": true,
"STRUCTURE": true,
"SUCCESSFUL": true,
"SWITCH": true,
"SYS_OP_ENFORCE_NOT_NULL$": true,
"SYS_OP_NTCIMG$": true,
"SYNONYM": true,
"SYSDATE": true,
"SYSDBA": true,
"SYSOPER": true,
"SYSTEM": true,
"TABLE": true,
"TABLES": true,
"TABLESPACE": true,
"TABLESPACE_NO": true,
"TABNO": true,
"TEMPORARY": true,
"THAN": true,
"THE": true,
"THEN": true,
"THREAD": true,
"TIMESTAMP": true,
"TIME": true,
"TO": true,
"TOPLEVEL": true,
"TRACE": true,
"TRACING": true,
"TRANSACTION": true,
"TRANSITIONAL": true,
"TRIGGER": true,
"TRIGGERS": true,
"TRUE": true,
"TRUNCATE": true,
"TX": true,
"TYPE": true,
"UB2": true,
"UBA": true,
"UID": true,
"UNARCHIVED": true,
"UNDO": true,
"UNION": true,
"UNIQUE": true,
"UNLIMITED": true,
"UNLOCK": true,
"UNRECOVERABLE": true,
"UNTIL": true,
"UNUSABLE": true,
"UNUSED": true,
"UPDATABLE": true,
"UPDATE": true,
"USAGE": true,
"USE": true,
"USER": true,
"USING": true,
"VALIDATE": true,
"VALIDATION": true,
"VALUE": true,
"VALUES": true,
"VARCHAR": true,
"VARCHAR2": true,
"VARYING": true,
"VIEW": true,
"WHEN": true,
"WHENEVER": true,
"WHERE": true,
"WITH": true,
"WITHOUT": true,
"WORK": true,
"WRITE": true,
"WRITEDOWN": true,
"WRITEUP": true,
"XID": true,
"YEAR": true,
"ZONE": true,
}
oracleQuoter = schemas.Quoter{
Prefix: '"',
Suffix: '"',
IsReserved: schemas.AlwaysReserve,
}
)
type oracle struct {
Base
}
func (db *oracle) Init(uri *URI) error {
db.quoter = oracleQuoter
return db.Base.Init(db, uri)
}
func (db *oracle) Version(ctx context.Context, queryer core.Queryer) (*schemas.Version, error) {
rows, err := queryer.QueryContext(ctx, "select * from v$version where banner like 'Oracle%'")
if err != nil {
return nil, err
}
defer rows.Close()
var version string
if !rows.Next() {
return nil, errors.New("unknow version")
}
if err := rows.Scan(&version); err != nil {
return nil, err
}
return &schemas.Version{
Number: version,
}, nil
}
func (db *oracle) SQLType(c *schemas.Column) string {
var res string
switch t := c.SQLType.Name; t {
case schemas.Bit, schemas.TinyInt, schemas.SmallInt, schemas.MediumInt, schemas.Int, schemas.Integer, schemas.BigInt, schemas.Bool, schemas.Serial, schemas.BigSerial:
res = "NUMBER"
case schemas.Binary, schemas.VarBinary, schemas.Blob, schemas.TinyBlob, schemas.MediumBlob, schemas.LongBlob, schemas.Bytea:
return schemas.Blob
case schemas.Time, schemas.DateTime, schemas.TimeStamp:
res = schemas.TimeStamp
case schemas.TimeStampz:
res = "TIMESTAMP WITH TIME ZONE"
case schemas.Float, schemas.Double, schemas.Numeric, schemas.Decimal:
res = "NUMBER"
case schemas.Text, schemas.MediumText, schemas.LongText, schemas.Json:
res = "CLOB"
case schemas.Char, schemas.Varchar, schemas.TinyText:
res = "VARCHAR2"
default:
res = t
}
hasLen1 := (c.Length > 0)
hasLen2 := (c.Length2 > 0)
if hasLen2 {
res += "(" + strconv.Itoa(c.Length) + "," + strconv.Itoa(c.Length2) + ")"
} else if hasLen1 {
res += "(" + strconv.Itoa(c.Length) + ")"
}
return res
}
func (db *oracle) AutoIncrStr() string {
return "AUTO_INCREMENT"
}
func (db *oracle) IsReserved(name string) bool {
_, ok := oracleReservedWords[strings.ToUpper(name)]
return ok
}
func (db *oracle) DropTableSQL(tableName string) (string, bool) {
return fmt.Sprintf("DROP TABLE `%s`", tableName), false
}
func (db *oracle) CreateTableSQL(table *schemas.Table, tableName string) ([]string, bool) {
var sql = "CREATE TABLE "
if tableName == "" {
tableName = table.Name
}
quoter := db.Quoter()
sql += quoter.Quote(tableName) + " ("
pkList := table.PrimaryKeys
for _, colName := range table.ColumnsSeq() {
col := table.GetColumn(colName)
/*if col.IsPrimaryKey && len(pkList) == 1 {
sql += col.String(b.dialect)
} else {*/
s, _ := ColumnString(db, col, false)
sql += s
// }
sql = strings.TrimSpace(sql)
sql += ", "
}
if len(pkList) > 0 {
sql += "PRIMARY KEY ( "
sql += quoter.Join(pkList, ",")
sql += " ), "
}
sql = sql[:len(sql)-2] + ")"
return []string{sql}, false
}
func (db *oracle) SetQuotePolicy(quotePolicy QuotePolicy) {
switch quotePolicy {
case QuotePolicyNone:
var q = oracleQuoter
q.IsReserved = schemas.AlwaysNoReserve
db.quoter = q
case QuotePolicyReserved:
var q = oracleQuoter
q.IsReserved = db.IsReserved
db.quoter = q
case QuotePolicyAlways:
fallthrough
default:
db.quoter = oracleQuoter
}
}
func (db *oracle) IndexCheckSQL(tableName, idxName string) (string, []interface{}) {
args := []interface{}{tableName, idxName}
return `SELECT INDEX_NAME FROM USER_INDEXES ` +
`WHERE TABLE_NAME = :1 AND INDEX_NAME = :2`, args
}
func (db *oracle) IsTableExist(queryer core.Queryer, ctx context.Context, tableName string) (bool, error) {
return db.HasRecords(queryer, ctx, `SELECT table_name FROM user_tables WHERE table_name = :1`, tableName)
}
func (db *oracle) IsColumnExist(queryer core.Queryer, ctx context.Context, tableName, colName string) (bool, error) {
args := []interface{}{tableName, colName}
query := "SELECT column_name FROM USER_TAB_COLUMNS WHERE table_name = :1" +
" AND column_name = :2"
return db.HasRecords(queryer, ctx, query, args...)
}
func (db *oracle) GetColumns(queryer core.Queryer, ctx context.Context, tableName string) ([]string, map[string]*schemas.Column, error) {
args := []interface{}{tableName}
s := "SELECT column_name,data_default,data_type,data_length,data_precision,data_scale," +
"nullable FROM USER_TAB_COLUMNS WHERE table_name = :1"
rows, err := queryer.QueryContext(ctx, s, args...)
if err != nil {
return nil, nil, err
}
defer rows.Close()
cols := make(map[string]*schemas.Column)
colSeq := make([]string, 0)
for rows.Next() {
col := new(schemas.Column)
col.Indexes = make(map[string]int)
var colName, colDefault, nullable, dataType, dataPrecision, dataScale *string
var dataLen int
err = rows.Scan(&colName, &colDefault, &dataType, &dataLen, &dataPrecision,
&dataScale, &nullable)
if err != nil {
return nil, nil, err
}
col.Name = strings.Trim(*colName, `" `)
if colDefault != nil {
col.Default = *colDefault
col.DefaultIsEmpty = false
}
if *nullable == "Y" {
col.Nullable = true
} else {
col.Nullable = false
}
var ignore bool
var dt string
var len1, len2 int
dts := strings.Split(*dataType, "(")
dt = dts[0]
if len(dts) > 1 {
lens := strings.Split(dts[1][:len(dts[1])-1], ",")
if len(lens) > 1 {
len1, _ = strconv.Atoi(lens[0])
len2, _ = strconv.Atoi(lens[1])
} else {
len1, _ = strconv.Atoi(lens[0])
}
}
switch dt {
case "VARCHAR2":
col.SQLType = schemas.SQLType{Name: schemas.Varchar, DefaultLength: len1, DefaultLength2: len2}
case "NVARCHAR2":
col.SQLType = schemas.SQLType{Name: schemas.NVarchar, DefaultLength: len1, DefaultLength2: len2}
case "TIMESTAMP WITH TIME ZONE":
col.SQLType = schemas.SQLType{Name: schemas.TimeStampz, DefaultLength: 0, DefaultLength2: 0}
case "NUMBER":
col.SQLType = schemas.SQLType{Name: schemas.Double, DefaultLength: len1, DefaultLength2: len2}
case "LONG", "LONG RAW":
col.SQLType = schemas.SQLType{Name: schemas.Text, DefaultLength: 0, DefaultLength2: 0}
case "RAW":
col.SQLType = schemas.SQLType{Name: schemas.Binary, DefaultLength: 0, DefaultLength2: 0}
case "ROWID":
col.SQLType = schemas.SQLType{Name: schemas.Varchar, DefaultLength: 18, DefaultLength2: 0}
case "AQ$_SUBSCRIBERS":
ignore = true
default:
col.SQLType = schemas.SQLType{Name: strings.ToUpper(dt), DefaultLength: len1, DefaultLength2: len2}
}
if ignore {
continue
}
if _, ok := schemas.SqlTypes[col.SQLType.Name]; !ok {
return nil, nil, fmt.Errorf("Unknown colType %v %v", *dataType, col.SQLType)
}
col.Length = dataLen
if col.SQLType.IsText() || col.SQLType.IsTime() {
if !col.DefaultIsEmpty {
col.Default = "'" + col.Default + "'"
}
}
cols[col.Name] = col
colSeq = append(colSeq, col.Name)
}
return colSeq, cols, nil
}
func (db *oracle) GetTables(queryer core.Queryer, ctx context.Context) ([]*schemas.Table, error) {
args := []interface{}{}
s := "SELECT table_name FROM user_tables"
rows, err := queryer.QueryContext(ctx, s, args...)
if err != nil {
return nil, err
}
defer rows.Close()
tables := make([]*schemas.Table, 0)
for rows.Next() {
table := schemas.NewEmptyTable()
err = rows.Scan(&table.Name)
if err != nil {
return nil, err
}
tables = append(tables, table)
}
return tables, nil
}
func (db *oracle) GetIndexes(queryer core.Queryer, ctx context.Context, tableName string) (map[string]*schemas.Index, error) {
args := []interface{}{tableName}
s := "SELECT t.column_name,i.uniqueness,i.index_name FROM user_ind_columns t,user_indexes i " +
"WHERE t.index_name = i.index_name and t.table_name = i.table_name and t.table_name =:1"
rows, err := queryer.QueryContext(ctx, s, args...)
if err != nil {
return nil, err
}
defer rows.Close()
indexes := make(map[string]*schemas.Index, 0)
for rows.Next() {
var indexType int
var indexName, colName, uniqueness string
err = rows.Scan(&colName, &uniqueness, &indexName)
if err != nil {
return nil, err
}
indexName = strings.Trim(indexName, `" `)
var isRegular bool
if strings.HasPrefix(indexName, "IDX_"+tableName) || strings.HasPrefix(indexName, "UQE_"+tableName) {
indexName = indexName[5+len(tableName):]
isRegular = true
}
if uniqueness == "UNIQUE" {
indexType = schemas.UniqueType
} else {
indexType = schemas.IndexType
}
var index *schemas.Index
var ok bool
if index, ok = indexes[indexName]; !ok {
index = new(schemas.Index)
index.Type = indexType
index.Name = indexName
index.IsRegular = isRegular
indexes[indexName] = index
}
index.AddColumn(colName)
}
return indexes, nil
}
func (db *oracle) Filters() []Filter {
return []Filter{
&SeqFilter{Prefix: ":", Start: 1},
}
}
type godrorDriver struct {
}
func (cfg *godrorDriver) Parse(driverName, dataSourceName string) (*URI, error) {
db := &URI{DBType: schemas.ORACLE}
dsnPattern := regexp.MustCompile(
`^(?:(?P<user>.*?)(?::(?P<passwd>.*))?@)?` + // [user[:password]@]
`(?:(?P<net>[^\(]*)(?:\((?P<addr>[^\)]*)\))?)?` + // [net[(addr)]]
`\/(?P<dbname>.*?)` + // /dbname
`(?:\?(?P<params>[^\?]*))?$`) // [?param1=value1&paramN=valueN]
matches := dsnPattern.FindStringSubmatch(dataSourceName)
// tlsConfigRegister := make(map[string]*tls.Config)
names := dsnPattern.SubexpNames()
for i, match := range matches {
switch names[i] {
case "dbname":
db.DBName = match
}
}
if db.DBName == "" {
return nil, errors.New("dbname is empty")
}
return db, nil
}
type oci8Driver struct {
}
// dataSourceName=user/password@ipv4:port/dbname
// dataSourceName=user/password@[ipv6]:port/dbname
func (p *oci8Driver) Parse(driverName, dataSourceName string) (*URI, error) {
db := &URI{DBType: schemas.ORACLE}
dsnPattern := regexp.MustCompile(
`^(?P<user>.*)\/(?P<password>.*)@` + // user:password@
`(?P<net>.*)` + // ip:port
`\/(?P<dbname>.*)`) // dbname
matches := dsnPattern.FindStringSubmatch(dataSourceName)
names := dsnPattern.SubexpNames()
for i, match := range matches {
switch names[i] {
case "dbname":
db.DBName = match
}
}
if db.DBName == "" && len(matches) != 0 {
return nil, errors.New("dbname is empty")
}
return db, nil
}