sq/drivers/mysql/render.go
Neil O'Toole 79e1afd64f
SQL rownum() func ()
* Implemented SLQ rownum() func
2023-11-19 23:44:36 -07:00

252 lines
6.3 KiB
Go

package mysql
import (
"bytes"
"fmt"
"strings"
"github.com/neilotoole/sq/libsq/ast"
"github.com/neilotoole/sq/libsq/ast/render"
"github.com/neilotoole/sq/libsq/core/errz"
"github.com/neilotoole/sq/libsq/core/kind"
"github.com/neilotoole/sq/libsq/core/sqlmodel"
"github.com/neilotoole/sq/libsq/core/stringz"
)
func dbTypeNameFromKind(knd kind.Kind) string {
switch knd { //nolint:exhaustive // ignore kind.Unknown and kind.Null
case kind.Text:
return "TEXT"
case kind.Int:
return "INT"
case kind.Float:
return "DOUBLE"
case kind.Decimal:
return "DECIMAL"
case kind.Bool:
return "TINYINT(1)"
case kind.Datetime:
return "DATETIME"
case kind.Time:
return "TIME"
case kind.Date:
return "DATE"
case kind.Bytes:
return "BLOB"
default:
panic(fmt.Sprintf("unsupported data kind {%s}", knd))
}
}
// createTblKindDefaults is a map of Kind to the value
// to use for a column's DEFAULT clause in a CREATE TABLE statement.
//
// Note that MySQL (at least of v5.6) doesn't support DEFAULT values
// for TEXT or BLOB columns.
// https://bugs.mysql.com/bug.php?id=21532
var createTblKindDefaults = map[kind.Kind]string{ //nolint:exhaustive
kind.Text: ``,
kind.Int: `DEFAULT 0`,
kind.Float: `DEFAULT 0`,
kind.Decimal: `DEFAULT 0`,
kind.Bool: `DEFAULT 0`,
kind.Datetime: `DEFAULT '1970-01-01 00:00:00'`,
kind.Date: `DEFAULT '1970-01-01'`,
kind.Time: `DEFAULT '00:00:00'`,
kind.Bytes: ``,
kind.Unknown: ``,
}
//nolint:funlen
func buildCreateTableStmt(tblDef *sqlmodel.TableDef) string {
buf := &bytes.Buffer{}
cols := make([]string, len(tblDef.Cols))
for i, col := range tblDef.Cols {
buf.WriteRune('`')
buf.WriteString(col.Name)
buf.WriteString("` ")
buf.WriteString(dbTypeNameFromKind(col.Kind))
if col.HasDefault {
buf.WriteRune(' ')
buf.WriteString(createTblKindDefaults[col.Kind])
}
if col.NotNull {
buf.WriteString(" NOT NULL")
}
if col.Name == tblDef.PKColName && tblDef.AutoIncrement {
buf.WriteString(" AUTO_INCREMENT")
}
cols[i] = buf.String()
buf.Reset()
}
pk := ""
if tblDef.PKColName != "" {
buf.WriteString("PRIMARY KEY (`")
buf.WriteString(tblDef.PKColName)
buf.WriteString("`),\n")
buf.WriteString("UNIQUE KEY `")
buf.WriteString(tblDef.Name)
buf.WriteRune('_')
buf.WriteString(tblDef.PKColName)
buf.WriteString("_uindex` (`")
buf.WriteString(tblDef.PKColName)
buf.WriteString("`)")
pk = buf.String()
}
uniq := ""
buf.Reset()
for _, col := range tblDef.Cols {
if col.Name == tblDef.PKColName {
// if the table has a PK, then we've already added a unique constraint for it above
continue
}
if col.Unique {
if buf.Len() > 0 {
buf.WriteString(",\n")
}
buf.WriteString("UNIQUE KEY `")
buf.WriteString(tblDef.Name)
buf.WriteRune('_')
buf.WriteString(col.Name)
buf.WriteString("_uindex` (`")
buf.WriteString(col.Name)
buf.WriteString("`)")
}
}
uniq = buf.String()
fk := ""
buf.Reset()
for _, col := range tblDef.Cols {
if col.ForeignKey == nil {
continue
}
if buf.Len() > 0 {
buf.WriteString(",\n")
}
buf.WriteString("KEY `")
buf.WriteString(tblDef.Name)
buf.WriteRune('_')
buf.WriteString(col.Name)
buf.WriteRune('_')
buf.WriteString(col.ForeignKey.RefTable)
buf.WriteRune('_')
buf.WriteString(col.ForeignKey.RefCol)
buf.WriteString("_key` (`")
buf.WriteString(col.Name)
buf.WriteString("`),\nCONSTRAINT `")
buf.WriteString(tblDef.Name)
buf.WriteRune('_')
buf.WriteString(col.Name)
buf.WriteRune('_')
buf.WriteString(col.ForeignKey.RefTable)
buf.WriteRune('_')
buf.WriteString(col.ForeignKey.RefCol)
buf.WriteString("_fk` FOREIGN KEY (`")
buf.WriteString(col.Name)
buf.WriteString("`) REFERENCES `")
buf.WriteString(col.ForeignKey.RefTable)
buf.WriteString("` (`")
buf.WriteString(col.ForeignKey.RefCol)
buf.WriteString("`) ON DELETE ")
if col.ForeignKey.OnDelete == "" {
buf.WriteString("CASCADE")
} else {
buf.WriteString(col.ForeignKey.OnDelete)
}
buf.WriteString(" ON UPDATE ")
if col.ForeignKey.OnUpdate == "" {
buf.WriteString("CASCADE")
} else {
buf.WriteString(col.ForeignKey.OnUpdate)
}
}
fk = buf.String()
buf.Reset()
buf.WriteString("CREATE TABLE `")
buf.WriteString(tblDef.Name)
buf.WriteString("` (\n")
for x := 0; x < len(cols)-1; x++ {
buf.WriteString(cols[x])
buf.WriteString(",\n")
}
buf.WriteString(cols[len(cols)-1])
if pk != "" {
buf.WriteString(",\n")
buf.WriteString(pk)
}
if uniq != "" {
buf.WriteString(",\n")
buf.WriteString(uniq)
}
if fk != "" {
buf.WriteString(",\n")
buf.WriteString(fk)
}
buf.WriteString("\n)")
return buf.String()
}
func buildUpdateStmt(tbl string, cols []string, where string) (string, error) {
if len(cols) == 0 {
return "", errz.Errorf("no columns provided")
}
buf := strings.Builder{}
buf.WriteString("UPDATE `")
buf.WriteString(tbl)
buf.WriteString("` SET `")
buf.WriteString(strings.Join(cols, "` = ?, `"))
buf.WriteString("` = ?")
if where != "" {
buf.WriteString(" WHERE ")
buf.WriteString(where)
}
return buf.String(), nil
}
// renderFuncRowNum renders the rownum() function.
//
// MySQL didn't introduce ROW_NUMBER() until 8.0, and we're still
// trying to support 5.6 and 5.7. So, we're using a hack, as
// described here: https://www.mysqltutorial.org/mysql-row_number/
//
// SET @row_number = 0;
// SELECT
// (@row_number:=@row_number + 1) AS num,
// actor_id,
// first_name,
// last_name
// FROM actor
// ORDER BY first_name
//
// The function puts the SET statement into the PreExecStmts fragment,
// which then gets executed before the main body of the query.
//
// For MySQL 8+, we could use the ROW_NUMBER() function, but right now
// the code isn't really set up to execute different impls for different
// driver versions. Although, this is probably something we need to face up to.
func renderFuncRowNum(rc *render.Context, _ *ast.FuncNode) (string, error) { //nolint:unparam
// We use a unique variable name to avoid collisions if there are
// multiple uses of rownum() in the same query.
variable := "@row_number_" + stringz.Uniq8()
rc.Fragments.PreExecStmts = append(rc.Fragments.PreExecStmts, "SET "+variable+" = 0;")
rc.Fragments.PostExecStmts = append(rc.Fragments.PostExecStmts, "SET "+variable+" = NULL;")
// e.g. (@row_number_abcd1234:=@row_number_abcd1234 + 1)
return "(" + variable + ":=" + variable + " + 1)", nil
}