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schema_versions.go
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/
schema_versions.go
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package storage_sql
import (
"database/sql"
)
func checkSchemaVersionsTable(tx *sql.Tx) error {
_, err := tx.Exec(
`CREATE TABLE IF NOT EXISTS schema_version (
tablename TEXT PRIMARY KEY,
version INTEGER NOT NULL
)`)
return err
}
func schemaTableExists(tx *sql.Tx, table string) bool {
rows, err := tx.Query(`SELECT * FROM ` + table + ` LIMIT 1`)
if nil != rows {
rows.Close()
}
return nil == err
}
func schemaGetVersion(tx *sql.Tx, table string) (*int64, error) {
if rows, err := tx.Query(
`SELECT version
FROM schema_version
WHERE tablename = $1`, table); nil != err {
return nil, err
} else {
defer rows.Close()
if !rows.Next() {
if schemaTableExists(tx, table) {
var version int64 = -1
// don't know the version, but it exists; return "-1" as version
return &version, nil
} else {
// not found
return nil, nil
}
}
var version int64
if err := rows.Scan(&version); nil != err {
return nil, err
}
return &version, nil
}
}
func schemaSetVersion(tx *sql.Tx, table string, version int64) error {
_, err := tx.Exec(
`INSERT OR REPLACE INTO schema_version
(tablename, version) VALUES ($1, $2)`, table, version)
return err
}