我从Excel导入为变量名，然后将reshape导入到“ observations”中，这是一系列表示日期的字符串（5s）。
这些日期（存储在变量daate中）的格式为ddnn20Y：1108，表示2008年1月1日； 1912，表示2012年9月1日；或11210，表示2010年12月1日。也就是说，它们是作为字符串保存的 not Stata内部格式（SIF）日期！
我尝试过的事情超出了我的记忆（即：直接使用format daate %tdddnn20YY或gen date = date(daate, "DM20Y")进行格式化）。
我已经阅读了help datetime，并试图实现HRF-to-SIF Functions（在我看来，这应该是第一步），但没有成功。
This other question几乎可以解决这个问题：首先是destring将daate改成int，然后是gen date = mofd(daate); format date %tm。但这是另一种失败的方法。
示例数据：
* Example generated by -dataex-. To install: ssc install dataex
clear
input str12 isin str5 daate double price
"AEA000201011" "11008" 3.53
"AEA000201011" "11009" 2.44
"AEA000201011" "11010" 2.32
"AEA000201011" "11011" 2.86
"AEA000201011" "11012" 3.28
"AEA000201011" "11013" 4.93
"AEA000201011" "11014" 8.6
"AEA000201011" "11015" 7.75
"AEA000201011" "1108" 5.34
"AEA000201011" "1109" 1.78
"AEA000201011" "1110" 1.61
"AEA000201011" "11108" 2.63
"AEA000201011" "11109" 2
"AEA000201011" "1111" 2.14
"AEA000201011" "11110" 2.43
"AEA000201011" "11111" 2.94
"AEA000201011" "11112" 3.29
"AEA000201011" "11113" 5
"AEA000201011" "11114" 7.97
"AEA000201011" "11115" 7.09
"AEA000201011" "1112" 2.77
"AEA000201011" "1113" 3.01
"AEA000201011" "1114" 6.5
"AEA000201011" "1115" 7.03
"AEA000201011" "11208" 2.55
"AEA000201011" "11209" 1.82
"AEA000201011" "11210" 2.3
"AEA000201011" "11211" 2.85
"AEA000201011" "11212" 2.98
"AEA000201011" "11213" 5.4
"AEA000201011" "11214" 6.66
"AEA000201011" "11215" 6.25
"AEA000201011" "1208" 5.58
"AEA000201011" "1209" 1.48
"AEA000201011" "1210" 1.59
"AEA000201011" "1211" 2.15
"AEA000201011" "1212" 2.91
"AEA000201011" "1213" 3.6
"AEA000201011" "1214" 6.79
"AEA000201011" "1215" 7.18
"AEA000201011" "1308" 5.37
"AEA000201011" "1309" 1.74
"AEA000201011" "1310" 1.66
"AEA000201011" "1311" 2.21
"AEA000201011" "1312" 3.23
"AEA000201011" "1313" 4.01
"AEA000201011" "1314" 7.15
"AEA000201011" "1315" 7.6
"AEA000201011" "1408" 5.41
"AEA000201011" "1409" 1.64
"AEA000201011" "1410" 2.09
"AEA000201011" "1411" 2.52
"AEA000201011" "1412" 3.23
"AEA000201011" "1413" 4.13
"AEA000201011" "1414" 7.36
"AEA000201011" "1415" 6.66
"AEA000201011" "1508" 5.82
"AEA000201011" "1509" 1.56
"AEA000201011" "1510" 1.89
"AEA000201011" "1511" 2.87
"AEA000201011" "1512" 3.31
"AEA000201011" "1513" 4.66
"AEA000201011" "1514" 7.8
"AEA000201011" "1515" 7.36
"AEA000201011" "1608" 5.25
"AEA000201011" "1609" 1.78
"AEA000201011" "1610" 1.63
"AEA000201011" "1611" 2.92
"AEA000201011" "1612" 2.91
"AEA000201011" "1613" 4.95
"AEA000201011" "1614" 8.65
"AEA000201011" "1615" 7.57
"AEA000201011" "1708" 5.2
"AEA000201011" "1709" 1.59
"AEA000201011" "1710" 1.57
"AEA000201011" "1711" 3.13
"AEA000201011" "1712" 3.36
"AEA000201011" "1713" 5
"AEA000201011" "1714" 7.6
"AEA000201011" "1715" 7.55
"AEA000201011" "1808" 5.04
"AEA000201011" "1809" 1.99
"AEA000201011" "1810" 1.65
"AEA000201011" "1811" 3.11
"AEA000201011" "1812" 3.37
"AEA000201011" "1813" 5.33
"AEA000201011" "1814" 8.7
"AEA000201011" "1815" 8.12
"AEA000201011" "1908" 4.1
"AEA000201011" "1909" 1.98
"AEA000201011" "1910" 1.68
"AEA000201011" "1911" 2.98
"AEA000201011" "1912" 3.3
"AEA000201011" "1913" 5.01
"AEA000201011" "1914" 8.11
"AEA000201011" "1915" 7.76
"AEA000701010" "11008" 2.14
"AEA000701010" "11009" .78
"AEA000701010" "11010" .67
"AEA000701010" "11011" .58
end
答案 0 :(得分：2)
此解决方案依赖于首先整理原始文档以更接近Stata的偏好，因此可以进行仔细检查。我们不需要您所有的数据示例（谢谢）。正如@Pearly Spencer指出的那样，这些实际上是每月日期，表示为每日日期。
* Example generated by -dataex-. To install: ssc install dataex
clear
input str5 daate
"11008"
"11009"
"11010"
"11011"
"11012"
"11013"
"11014"
"11015"
"1108"
"1109"
"1110"
"11108"
"11109"
"1111"
"11110"
"11111"
"11112"
"11113"
"11114"
"11115"
"1112"
"1113"
"1114"
"1115"
"11208"
"11209"
"11210"
"11211"
"11212"
"11213"
"11214"
"11215"
"1208"
"1209"
"1210"
"1211"
"1212"
"1213"
"1214"
"1215"
"1308"
"1309"
"1310"
"1311"
"1312"
"1313"
"1314"
"1315"
"1408"
"1409"
"1410"
"1411"
"1412"
"1413"
"1414"
"1415"
"1508"
"1509"
"1510"
"1511"
"1512"
"1513"
"1514"
"1515"
"1608"
"1609"
"1610"
"1611"
"1612"
"1613"
"1614"
"1615"
"1708"
"1709"
"1710"
"1711"
"1712"
"1713"
"1714"
"1715"
"1808"
"1809"
"1810"
"1811"
"1812"
"1813"
"1814"
"1815"
"1908"
"1909"
"1910"
"1911"
"1912"
"1913"
"1914"
"1915"
end
gen better = substr(daate, 1, 1) + ///
" " + substr(daate, 2, length(daate) - 3) + ///
" 20" + substr(daate, -2, 2)
gen mdate = mofd(daily(better, "DMY"))
sort mdate
format mdate %tm
gen year = year(daily(better, "DMY"))
list if year <= 2009 , sepby(year)
+------------------------------------+
| daate better mdate year |
|------------------------------------|
1. | 1108 1 1 2008 2008m1 2008 |
2. | 1208 1 2 2008 2008m2 2008 |
3. | 1308 1 3 2008 2008m3 2008 |
4. | 1408 1 4 2008 2008m4 2008 |
5. | 1508 1 5 2008 2008m5 2008 |
6. | 1608 1 6 2008 2008m6 2008 |
7. | 1708 1 7 2008 2008m7 2008 |
8. | 1808 1 8 2008 2008m8 2008 |
9. | 1908 1 9 2008 2008m9 2008 |
10. | 11008 1 10 2008 2008m10 2008 |
11. | 11108 1 11 2008 2008m11 2008 |
12. | 11208 1 12 2008 2008m12 2008 |
|------------------------------------|
13. | 1109 1 1 2009 2009m1 2009 |
14. | 1209 1 2 2009 2009m2 2009 |
15. | 1309 1 3 2009 2009m3 2009 |
16. | 1409 1 4 2009 2009m4 2009 |
17. | 1509 1 5 2009 2009m5 2009 |
18. | 1609 1 6 2009 2009m6 2009 |
19. | 1709 1 7 2009 2009m7 2009 |
20. | 1809 1 8 2009 2009m8 2009 |
21. | 1909 1 9 2009 2009m9 2009 |
22. | 11009 1 10 2009 2009m10 2009 |
23. | 11109 1 11 2009 2009m11 2009 |
24. | 11209 1 12 2009 2009m12 2009 |
+------------------------------------+
答案 1 :(得分：2)
字符串到数字日期的转换功能（help datetime_translation）
不应与显示 format 的日期和时间混淆
（help datetime_display_formats）。
前者具有用于 masks 的专用代码，并且不接受后者的 details 代码。在您的示例中，ddnn20Y是显示格式的详细代码，因此不是date()函数的有效掩码。
日期时间转换的掩码需要D，M，Y和h的组合，
m，s代码。但是，实现方式取决于要翻译的人类可读形式的日期字符串。
例如，以下内容有效：
. display date("011008", "DM20Y")
17806
相反，下面的不是：
. display date("11008", "DM20Y")
.
任何偏离Stata日期时间翻译规范的字符串 应该首先使用内置字符串函数（如@NickCox的）进行操作 答案。