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query.go
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query.go
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// Copyright 2011-2018 Paul Ruane.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package database
import (
"database/sql"
"github.com/oniony/TMSU/entities"
)
// The complete set of queries.
func Queries(tx *Tx) (entities.Queries, error) {
sql := `
SELECT text
FROM query
ORDER BY text`
rows, err := tx.Query(sql)
if err != nil {
return nil, err
}
defer rows.Close()
return readQueries(rows, make(entities.Queries, 0, 10))
}
// Retrieves the specified query.
func Query(tx *Tx, text string) (*entities.Query, error) {
sql := `
SELECT 1
FROM query
WHERE text = ?`
rows, err := tx.Query(sql, text)
if err != nil {
return nil, err
}
defer rows.Close()
return readQuery(rows)
}
// Adds a query to the database.
func InsertQuery(tx *Tx, text string) (*entities.Query, error) {
sql := `
INSERT INTO query (text)
VALUES (?)`
result, err := tx.Exec(sql, text)
if err != nil {
return nil, err
}
rowsAffected, err := result.RowsAffected()
if err != nil {
return nil, err
}
if rowsAffected != 1 {
panic("expected exactly one row to be affected.")
}
return &entities.Query{text}, nil
}
// Removes a query from the database.
func DeleteQuery(tx *Tx, text string) error {
sql := `
DELETE FROM query
WHERE text = ?`
result, err := tx.Exec(sql, text)
if err != nil {
return err
}
rowsAffected, err := result.RowsAffected()
if err != nil {
return err
}
if rowsAffected == 0 {
return NoSuchQueryError{text}
}
if rowsAffected != 1 {
panic("expected exactly one row to be affected.")
}
return nil
}
// unexported
func readQuery(rows *sql.Rows) (*entities.Query, error) {
if !rows.Next() {
return nil, nil
}
if rows.Err() != nil {
return nil, rows.Err()
}
var text string
err := rows.Scan(&text)
if err != nil {
return nil, err
}
return &entities.Query{text}, nil
}
func readQueries(rows *sql.Rows, queries entities.Queries) (entities.Queries, error) {
for {
query, err := readQuery(rows)
if err != nil {
return nil, err
}
if query == nil {
break
}
queries = append(queries, query)
}
return queries, nil
}