// getWhereClause returns a whereClause based on desired upper and lower
// bounds for primary key.
func (qs *QuerySplitter) getWhereClause(whereClause *sqlparser.Where, bindVars map[string]interface{}, start, end sqltypes.Value) *sqlparser.Where {
var startClause *sqlparser.ComparisonExpr
var endClause *sqlparser.ComparisonExpr
var clauses sqlparser.BoolExpr
// No upper or lower bound, just return the where clause of original query
if start.IsNull() && end.IsNull() {
return whereClause
}
pk := &sqlparser.ColName{
Name: sqlparser.SQLName(qs.splitColumn),
}
if !start.IsNull() {
startClause = &sqlparser.ComparisonExpr{
Operator: sqlparser.GreaterEqualStr,
Left: pk,
Right: sqlparser.ValArg([]byte(":" + startBindVarName)),
}
bindVars[startBindVarName] = start.ToNative()
}
// splitColumn < end
if !end.IsNull() {
endClause = &sqlparser.ComparisonExpr{
Operator: sqlparser.LessThanStr,
Left: pk,
Right: sqlparser.ValArg([]byte(":" + endBindVarName)),
}
bindVars[endBindVarName] = end.ToNative()
}
if startClause == nil {
clauses = endClause
} else {
if endClause == nil {
clauses = startClause
} else {
// splitColumn >= start AND splitColumn < end
clauses = &sqlparser.AndExpr{
Left: startClause,
Right: endClause,
}
}
}
if whereClause != nil {
clauses = &sqlparser.AndExpr{
Left: &sqlparser.ParenBoolExpr{Expr: whereClause.Expr},
Right: &sqlparser.ParenBoolExpr{Expr: clauses},
}
}
return &sqlparser.Where{
Type: sqlparser.WhereStr,
Expr: clauses,
}
}