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Add Mssql pagination feature with cte

This commit is contained in:
cantasci 2018-01-11 17:03:20 +03:00
parent 5275c0de3f
commit 9477d3719c
1 changed files with 29 additions and 4 deletions
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33
statement.go
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@ -1091,9 +1091,10 @@ func (statement *Statement) genSelectSQL(columnStr, condSQL string) (a string, e
} }
if dialect.DBType() == core.MSSQL { if dialect.DBType() == core.MSSQL {
if statement.LimitN > 0 { // !cantasci! this condition is not necesarry for now.
top = fmt.Sprintf(" TOP %d ", statement.LimitN) /*if statement.LimitN > 0 {
} top = fmt.Sprintf(" TOP %d", statement.LimitN)
}*/
if statement.Start > 0 { if statement.Start > 0 {
var column string var column string
if len(statement.RefTable.PKColumns()) == 0 { if len(statement.RefTable.PKColumns()) == 0 {
@ -1132,7 +1133,7 @@ func (statement *Statement) genSelectSQL(columnStr, condSQL string) (a string, e
// !nashtsai! REVIEW Sprintf is considered slowest mean of string concatnation, better to work with builder pattern // !nashtsai! REVIEW Sprintf is considered slowest mean of string concatnation, better to work with builder pattern
a = fmt.Sprintf("SELECT %v%v%v%v%v", distinct, top, columnStr, fromStr, whereStr) a = fmt.Sprintf("SELECT %v%v%v%v%v", distinct, top, columnStr, fromStr, whereStr)
if len(mssqlCondi) > 0 { if statement.Start == 0 && len(mssqlCondi) > 0 {
if len(whereStr) > 0 { if len(whereStr) > 0 {
a += " AND " + mssqlCondi a += " AND " + mssqlCondi
} else { } else {
@ -1159,6 +1160,12 @@ func (statement *Statement) genSelectSQL(columnStr, condSQL string) (a string, e
if statement.Start != 0 || statement.LimitN != 0 { if statement.Start != 0 || statement.LimitN != 0 {
a = fmt.Sprintf("SELECT %v FROM (SELECT %v,ROWNUM RN FROM (%v) at WHERE ROWNUM <= %d) aat WHERE RN > %d", columnStr, columnStr, a, statement.Start+statement.LimitN, statement.Start) a = fmt.Sprintf("SELECT %v FROM (SELECT %v,ROWNUM RN FROM (%v) at WHERE ROWNUM <= %d) aat WHERE RN > %d", columnStr, columnStr, a, statement.Start+statement.LimitN, statement.Start)
} }
} else if dialect.DBType() == core.MSSQL {
if statement.Start != 0 || statement.LimitN != 0 {
// !cantasci! use cte for related query when limit and offset values are set, then return filtered result by [start, start+limitN]
offsetColumn := statement.getPrimaryColumnForOffset()
a = fmt.Sprintf("WITH SQLPaging AS (SELECT TOP(%d) ROW_NUMBER() OVER (ORDER BY %v ASC) AS RN, %v FROM(%v) AS TEMP_TABLE_NAME) SELECT %v FROM SQLPaging WITH(NOLOCK) WHERE RN > %d AND RN < %d", statement.LimitN+statement.Start, offsetColumn, columnStr, a, columnStr, statement.Start, statement.Start+statement.LimitN+1)
}
} }
if statement.IsForUpdate { if statement.IsForUpdate {
a = dialect.ForUpdateSql(a) a = dialect.ForUpdateSql(a)
@ -1167,6 +1174,24 @@ func (statement *Statement) genSelectSQL(columnStr, condSQL string) (a string, e
return return
} }
func (statement *Statement) getPrimaryColumnForOffset() string {
var column string
if len(statement.RefTable.PKColumns()) == 0 {
for _, index := range statement.RefTable.Indexes {
if len(index.Cols) == 1 {
column = index.Cols[0]
break
}
}
if len(column) == 0 {
column = statement.RefTable.ColumnsSeq()[0]
}
} else {
column = statement.RefTable.PKColumns()[0].Name
}
return column
}
func (statement *Statement) processIDParam() error { func (statement *Statement) processIDParam() error {
if statement.idParam == nil { if statement.idParam == nil {
return nil return nil