githaven/vendor/xorm.io/xorm/dialect_oracle.go
2019-10-17 11:26:49 +02:00

903 lines
28 KiB
Go

// 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 xorm
import (
"errors"
"fmt"
"regexp"
"strconv"
"strings"
"xorm.io/core"
)
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,
}
)
type oracle struct {
core.Base
}
func (db *oracle) Init(d *core.DB, uri *core.Uri, drivername, dataSourceName string) error {
return db.Base.Init(d, db, uri, drivername, dataSourceName)
}
func (db *oracle) SqlType(c *core.Column) string {
var res string
switch t := c.SQLType.Name; t {
case core.Bit, core.TinyInt, core.SmallInt, core.MediumInt, core.Int, core.Integer, core.BigInt, core.Bool, core.Serial, core.BigSerial:
res = "NUMBER"
case core.Binary, core.VarBinary, core.Blob, core.TinyBlob, core.MediumBlob, core.LongBlob, core.Bytea:
return core.Blob
case core.Time, core.DateTime, core.TimeStamp:
res = core.TimeStamp
case core.TimeStampz:
res = "TIMESTAMP WITH TIME ZONE"
case core.Float, core.Double, core.Numeric, core.Decimal:
res = "NUMBER"
case core.Text, core.MediumText, core.LongText, core.Json:
res = "CLOB"
case core.Char, core.Varchar, core.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) SupportInsertMany() bool {
return true
}
func (db *oracle) IsReserved(name string) bool {
_, ok := oracleReservedWords[name]
return ok
}
func (db *oracle) Quote(name string) string {
return "[" + name + "]"
}
func (db *oracle) SupportEngine() bool {
return false
}
func (db *oracle) SupportCharset() bool {
return false
}
func (db *oracle) SupportDropIfExists() bool {
return false
}
func (db *oracle) IndexOnTable() bool {
return false
}
func (db *oracle) DropTableSql(tableName string) string {
return fmt.Sprintf("DROP TABLE `%s`", tableName)
}
func (db *oracle) CreateTableSql(table *core.Table, tableName, storeEngine, charset string) string {
var sql string
sql = "CREATE TABLE "
if tableName == "" {
tableName = table.Name
}
sql += db.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 {*/
sql += col.StringNoPk(db)
// }
sql = strings.TrimSpace(sql)
sql += ", "
}
if len(pkList) > 0 {
sql += "PRIMARY KEY ( "
sql += db.Quote(strings.Join(pkList, db.Quote(",")))
sql += " ), "
}
sql = sql[:len(sql)-2] + ")"
if db.SupportEngine() && storeEngine != "" {
sql += " ENGINE=" + storeEngine
}
if db.SupportCharset() {
if len(charset) == 0 {
charset = db.URI().Charset
}
if len(charset) > 0 {
sql += " DEFAULT CHARSET " + charset
}
}
return sql
}
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) TableCheckSql(tableName string) (string, []interface{}) {
args := []interface{}{tableName}
return `SELECT table_name FROM user_tables WHERE table_name = :1`, args
}
func (db *oracle) MustDropTable(tableName string) error {
sql, args := db.TableCheckSql(tableName)
db.LogSQL(sql, args)
rows, err := db.DB().Query(sql, args...)
if err != nil {
return err
}
defer rows.Close()
if !rows.Next() {
return nil
}
sql = "Drop Table \"" + tableName + "\""
db.LogSQL(sql, args)
_, err = db.DB().Exec(sql)
return err
}
/*func (db *oracle) ColumnCheckSql(tableName, colName string) (string, []interface{}) {
args := []interface{}{strings.ToUpper(tableName), strings.ToUpper(colName)}
return "SELECT column_name FROM USER_TAB_COLUMNS WHERE table_name = ?" +
" AND column_name = ?", args
}*/
func (db *oracle) IsColumnExist(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"
db.LogSQL(query, args)
rows, err := db.DB().Query(query, args...)
if err != nil {
return false, err
}
defer rows.Close()
if rows.Next() {
return true, nil
}
return false, nil
}
func (db *oracle) GetColumns(tableName string) ([]string, map[string]*core.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"
db.LogSQL(s, args)
rows, err := db.DB().Query(s, args...)
if err != nil {
return nil, nil, err
}
defer rows.Close()
cols := make(map[string]*core.Column)
colSeq := make([]string, 0)
for rows.Next() {
col := new(core.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 = core.SQLType{Name: core.Varchar, DefaultLength: len1, DefaultLength2: len2}
case "NVARCHAR2":
col.SQLType = core.SQLType{Name: core.NVarchar, DefaultLength: len1, DefaultLength2: len2}
case "TIMESTAMP WITH TIME ZONE":
col.SQLType = core.SQLType{Name: core.TimeStampz, DefaultLength: 0, DefaultLength2: 0}
case "NUMBER":
col.SQLType = core.SQLType{Name: core.Double, DefaultLength: len1, DefaultLength2: len2}
case "LONG", "LONG RAW":
col.SQLType = core.SQLType{Name: core.Text, DefaultLength: 0, DefaultLength2: 0}
case "RAW":
col.SQLType = core.SQLType{Name: core.Binary, DefaultLength: 0, DefaultLength2: 0}
case "ROWID":
col.SQLType = core.SQLType{Name: core.Varchar, DefaultLength: 18, DefaultLength2: 0}
case "AQ$_SUBSCRIBERS":
ignore = true
default:
col.SQLType = core.SQLType{Name: strings.ToUpper(dt), DefaultLength: len1, DefaultLength2: len2}
}
if ignore {
continue
}
if _, ok := core.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() ([]*core.Table, error) {
args := []interface{}{}
s := "SELECT table_name FROM user_tables"
db.LogSQL(s, args)
rows, err := db.DB().Query(s, args...)
if err != nil {
return nil, err
}
defer rows.Close()
tables := make([]*core.Table, 0)
for rows.Next() {
table := core.NewEmptyTable()
err = rows.Scan(&table.Name)
if err != nil {
return nil, err
}
tables = append(tables, table)
}
return tables, nil
}
func (db *oracle) GetIndexes(tableName string) (map[string]*core.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"
db.LogSQL(s, args)
rows, err := db.DB().Query(s, args...)
if err != nil {
return nil, err
}
defer rows.Close()
indexes := make(map[string]*core.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 = core.UniqueType
} else {
indexType = core.IndexType
}
var index *core.Index
var ok bool
if index, ok = indexes[indexName]; !ok {
index = new(core.Index)
index.Type = indexType
index.Name = indexName
index.IsRegular = isRegular
indexes[indexName] = index
}
index.AddColumn(colName)
}
return indexes, nil
}
func (db *oracle) Filters() []core.Filter {
return []core.Filter{&core.QuoteFilter{}, &core.SeqFilter{Prefix: ":", Start: 1}, &core.IdFilter{}}
}
type goracleDriver struct {
}
func (cfg *goracleDriver) Parse(driverName, dataSourceName string) (*core.Uri, error) {
db := &core.Uri{DbType: core.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) (*core.Uri, error) {
db := &core.Uri{DbType: core.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 == "" {
return nil, errors.New("dbname is empty")
}
return db, nil
}