1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
|
#' Backend: Teradata
#'
#' @description
#' See `vignette("translation-function")` and `vignette("translation-verb")` for
#' details of overall translation technology. Key differences for this backend
#' are:
#'
#' * Uses `TOP` instead of `LIMIT`
#' * Selection of user supplied translations
#'
#' Use `simulate_teradata()` with `lazy_frame()` to see simulated SQL without
#' converting to live access database.
#'
#' @name backend-teradata
#' @aliases NULL
#' @examples
#' library(dplyr, warn.conflicts = FALSE)
#'
#' lf <- lazy_frame(a = TRUE, b = 1, c = 2, d = "z", con = simulate_teradata())
#' lf %>% head()
NULL
#' @export
#' @rdname backend-teradata
simulate_teradata <- function() simulate_dbi("Teradata")
#' @export
dbplyr_edition.Teradata <- function(con) {
2L
}
#' @export
sql_query_select.Teradata <- function(con,
select,
from,
where = NULL,
group_by = NULL,
having = NULL,
window = NULL,
order_by = NULL,
limit = NULL,
distinct = FALSE,
...,
subquery = FALSE,
lvl = 0) {
# #685
# https://docs.teradata.com/r/2_MC9vCtAJRlKle2Rpb0mA/frQm7Rn09FJZZLQAuaUvJA
# You cannot specify these options in a SELECT statement that specifies the TOP n operator:
# * DISTINCT option
# * QUALIFY clause
# * SAMPLE clause
# * WITH clause
limit_needs_subquery <- is_true(distinct)
if (!is_null(limit) && limit_needs_subquery) {
unlimited_query <- sql_select_clauses(con,
select = sql_clause_select(con, select, distinct, top = NULL),
from = sql_clause_from(from),
where = sql_clause_where(where),
group_by = sql_clause_group_by(group_by),
having = sql_clause_having(having),
window = sql_clause_window(window),
order_by = sql_clause_order_by(order_by, subquery, limit = NULL),
lvl = lvl + 1
)
alias <- unique_subquery_name()
from <- sql_query_wrap(con, unlimited_query, name = alias)
select_outer <- sql_star(con, alias)
out <- sql_select_clauses(con,
select = sql_clause_select(con, select_outer, distinct = FALSE, top = limit),
from = sql_clause_from(from),
where = NULL,
group_by = NULL,
having = NULL,
window = NULL,
order_by = NULL,
lvl = lvl
)
return(out)
}
sql_select_clauses(con,
select = sql_clause_select(con, select, distinct, top = limit),
from = sql_clause_from(from),
where = sql_clause_where(where),
group_by = sql_clause_group_by(group_by),
having = sql_clause_having(having),
window = sql_clause_window(window),
order_by = sql_clause_order_by(order_by, subquery, limit),
lvl = lvl
)
}
#' @export
sql_translation.Teradata <- function(con) {
sql_variant(
sql_translator(.parent = base_odbc_scalar,
`!=` = sql_infix("<>"),
bitwNot = sql_prefix("BITNOT", 1),
bitwAnd = sql_prefix("BITAND", 2),
bitwOr = sql_prefix("BITOR", 2),
bitwXor = sql_prefix("BITXOR", 2),
bitwShiftL = sql_prefix("SHIFTLEFT", 2),
bitwShiftR = sql_prefix("SHIFTRIGHT", 2),
as.numeric = function(x, digits = 9L) {
digits <- vctrs::vec_cast(digits, integer())
sql_expr(CAST(!!x %as% DECIMAL(12L, !!digits)))
},
as.double = sql_cast("NUMERIC"),
as.character = sql_cast("VARCHAR(MAX)"),
as.Date = teradata_as_date,
log10 = sql_prefix("LOG"),
log = sql_log(),
cot = sql_cot(),
quantile = sql_quantile("APPROX_PERCENTILE"),
median = sql_median("APPROX_PERCENTILE"),
nchar = sql_prefix("CHARACTER_LENGTH"),
ceil = sql_prefix("CEILING"),
ceiling = sql_prefix("CEILING"),
atan2 = function(x, y) {
sql_expr(ATAN2(!!y, !!x))
},
substr = function(x, start, stop) {
len <- stop - start + 1
sql_expr(SUBSTR(!!x, !!start, !!len))
},
startsWith = function(string, pattern) {
glue_sql2(sql_current_con(), "CAST(CASE WHEN INSTR({.val string}, {.val pattern}) = 1 THEN 1 ELSE 0 END AS INTEGER)")
},
paste = sql_paste_infix(" ", "||", function(x) sql_expr(!!x)),
paste0 = sql_paste_infix("", "||", function(x) sql_expr(!!x)),
row_number = win_rank("ROW_NUMBER", empty_order = TRUE),
# lubridate ---------------------------------------------------------------
# https://en.wikibooks.org/wiki/SQL_Dialects_Reference/Functions_and_expressions/Date_and_time_functions
as_date = teradata_as_date,
week = function(x){
sql_expr(WEEKNUMBER_OF_YEAR(!!x, 'iso'))
},
quarter = function(x) {
glue_sql2(sql_current_con(), "to_char({.val x}, 'q')")
}
),
sql_translator(.parent = base_odbc_agg,
var = sql_aggregate("VAR_SAMP", "var"),
row_number = win_rank("ROW_NUMBER", empty_order = TRUE),
weighted.mean = function(x, w, na.rm = T) {
# nocov start
win_over(
sql_expr(SUM((!!x * !!w))/SUM(!!w)),
win_current_group(),
win_current_group(),
win_current_frame()
)
# nocov end
}
),
sql_translator(.parent = base_odbc_win,
var = win_recycled("VAR_SAMP"),
row_number = win_rank("ROW_NUMBER", empty_order = TRUE),
lead = function(x, n = 1L, default = NA, order_by = NULL) {
win_over(
sql_expr(LEAD(!!x, !!n, !!default)),
win_current_group(),
order_by %||% win_current_group(),
win_current_frame()
)
},
lag = function(x, n = 1L, default = NA, order_by = NULL) {
win_over(
sql_expr(LAG(!!x, !!as.integer(n), !!default)),
win_current_group(),
order_by %||% win_current_group(),
win_current_frame()
)
},
cumsum = function(x, order_by = NULL, frame = c(-Inf, 0)) {
win_over(
sql_expr(SUM(!!x)),
win_current_group(),
order_by %||% win_current_group(),
frame %||% win_current_frame()
)
},
weighted.mean = function(x, w, na.rm = T) {
# nocov start
win_over(
sql_expr(SUM((!!x * !!w))/SUM(!!w)),
win_current_group(),
win_current_group(),
win_current_frame()
)
# nocov end
}
)
)
}
teradata_as_date <- function(x) {
xq <- enquo(x)
x_expr <- quo_get_expr(xq)
if (is.character(x_expr) && !is.sql(x_expr)) {
glue_sql2(sql_current_con(), "DATE {.val x}")
} else {
sql_cast("DATE")(x)
}
}
#' @export
sql_table_analyze.Teradata <- function(con, table, ...) {
# https://www.tutorialspoint.com/teradata/teradata_statistics.htm
glue_sql2(con, "COLLECT STATISTICS {.tbl table}")
}
utils::globalVariables(c("ATAN2", "SUBSTR", "DECIMAL", "WEEKNUMBER_OF_YEAR", "SUM"))
#' @export
#' @rdname win_over
win_rank_tdata <- function(f) {
lifecycle::deprecate_warn(
"2.4.0",
what = "win_rank_tdata()",
with = "win_rank()"
)
force(f)
function(order_by = NULL) {
order_by <- order_by %||% win_current_group()
if (is_empty(order_by)) order_by <- sql("(SELECT NULL)")
win_over(
sql(glue("{f}()")),
partition = win_current_group(),
order = order_by,
frame = win_current_frame()
)
}
}
|
