{"id":17215,"date":"2022-10-23T12:23:48","date_gmt":"2022-10-23T06:53:48","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-if-col_lengthemp_numemployee-is-not-null-equivalent-in-oracle-closed\/"},"modified":"2022-10-23T12:23:48","modified_gmt":"2022-10-23T06:53:48","slug":"solved-if-col_lengthemp_numemployee-is-not-null-equivalent-in-oracle-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-if-col_lengthemp_numemployee-is-not-null-equivalent-in-oracle-closed\/","title":{"rendered":"[Solved] IF COL_LENGTH(‘EMP_NUM’,’EMPLOYEE’) IS NOT NULL – EQUIVALENT IN ORACLE [closed]"},"content":{"rendered":"

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In Oracle, you have to use dynamic SQL as you can’t execute DDL in PL\/SQL as is<\/em>. Why PL\/SQL? Because IF-THEN-ELSE<\/code> is<\/em> PL\/SQL, not SQL.<\/p>\n

Presuming this is part of your PL\/SQL procedure, you’d then<\/p>\n

if col_length('EMP_NUM', 'EMPLOYEE') is not null then\n  execute immediate 'alter table employee modify emp_num not null';\nend if;\n<\/code><\/pre>\n
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That’s for the ALTER<\/code> part. However, as Oracle doesn’t have COL_LENGTH function (nor anything like that, as far as I can tell), you have to do it yourself. Here’s  an example:<\/p>\n
A table whose column allows nulls:<\/p>\n
SQL> create table employee (emp_num number);\n\nTable created.\n<\/code><\/pre>\n
Check the Null?<\/code> column – empty, so yes – it allows nulls.<\/p>\n
SQL> desc employee;\n Name                                      Null?    Type\n ----------------------------------------- -------- ----------------------------\n EMP_NUM                                            NUMBER\n<\/code><\/pre>\n
Query data dictionary to find column’s length:<\/p>\n
SQL> select data_length from user_tab_columns\n  2  where table_name=\"EMPLOYEE\"\n  3    and column_name=\"EMP_NUM\";\n\nDATA_LENGTH\n-----------\n         22\n<\/code><\/pre>\n
Finally, your future PL\/SQL procedure:<\/p>\n
SQL> declare\n  2    l_len number;\n  3  begin\n  4    select data_length\n  5      into l_len\n  6      from user_tab_columns\n  7      where table_name=\"EMPLOYEE\"\n  8        and column_name=\"EMP_NUM\";\n  9\n 10    if l_len is not null then\n 11       execute immediate 'alter table employee modify emp_num not null';\n 12    end if;\n 13  end;\n 14  \/\n\nPL\/SQL procedure successfully completed.\n\nSQL> desc employee;\n Name                                      Null?    Type\n ----------------------------------------- -------- ----------------------------\n EMP_NUM                                   NOT NULL NUMBER\n\nSQL>\n<\/code><\/pre>\n
As you can see, the Null?<\/code> column now contains NOT NULL<\/code> which means that ALTER TABLE<\/code> was successfully executed.<\/p>\n
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Additionally, you can even create your own function to query column’s data length and then use it in your procedure:<\/p>\n
SQL> create or replace function col_length(par_table in varchar2, par_column in varchar2)\n  2    return number\n  3  is\n  4    retval user_tab_columns.data_length%type;\n  5  begin\n  6    select data_length\n  7      into retval\n  8      from user_tab_columns\n  9      where table_name = par_table\n 10        and column_name = par_column;\n 11    return retval;\n 12  end;\n 13  \/\n\nFunction created.\n\nSQL> select col_length('EMPLOYEE', 'EMP_NUM') from dual;\n\nCOL_LENGTH('EMPLOYEE','EMP_NUM')\n--------------------------------\n                              22\n\nSQL>\n<\/code><\/pre>\n
Finally:<\/p>\n
SQL> drop table employee;\n\nTable dropped.\n\nSQL> create table employee (emp_num number);\n\nTable created.\n\nSQL> begin\n  2    if col_length('EMPLOYEE', 'EMP_NUM') is not null then\n  3       execute immediate 'alter table employee modify emp_num not null';\n  4    end if;\n  5  end;\n  6  \/\n\nPL\/SQL procedure successfully completed.\n\nSQL> desc employee;\n Name                                      Null?    Type\n ----------------------------------------- -------- ----------------------------\n EMP_NUM                                   NOT NULL NUMBER\n\nSQL>\n<\/code><\/pre>\n<\/p><\/div>\n
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solved IF COL_LENGTH(‘EMP_NUM’,’EMPLOYEE’) IS NOT NULL – EQUIVALENT IN ORACLE [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] In Oracle, you have to use dynamic SQL as you can’t execute DDL in PL\/SQL as is. Why PL\/SQL? Because IF-THEN-ELSE is PL\/SQL, not SQL. Presuming this is part of your PL\/SQL procedure, you’d then if col_length(‘EMP_NUM’, ‘EMPLOYEE’) is not null then execute immediate ‘alter table employee modify emp_num not null’; end if; That’s … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[838,1244,500,1009],"class_list":["post-17215","post","type-post","status-publish","format-standard","hentry","category-solved","tag-oracle","tag-oracle11g","tag-sql-server","tag-tsql"],"yoast_head":"\n[Solved] IF COL_LENGTH('EMP_NUM','EMPLOYEE') IS NOT NULL - EQUIVALENT IN ORACLE [closed] - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-if-col_lengthemp_numemployee-is-not-null-equivalent-in-oracle-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] IF COL_LENGTH('EMP_NUM','EMPLOYEE') IS NOT NULL - EQUIVALENT IN ORACLE [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] In Oracle, you have to use dynamic SQL as you can’t execute DDL in PL\/SQL as is. Why PL\/SQL? Because IF-THEN-ELSE is PL\/SQL, not SQL. Presuming this is part of your PL\/SQL procedure, you’d then if col_length('EMP_NUM', 'EMPLOYEE') is not null then execute immediate 'alter table employee modify emp_num not null'; end if; That’s ... 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