string-constant

问题 #include<stdio.h> #include<string.h> int main() { int i, n; char *x="Alice"; // ....... 1 n = strlen(x); // ....... 2 *x = x[n]; // ....... 3 for(i=0; i<=n; i++) { printf("%s ", x); x++; } printf("\n"); return 0; } String constant cannot be modified. In the above code *x means 'A'. In line 3 we are trying to modify a string constant. Is it correct to write that statement? When I run this code on Linux , I got segmentation fault . But on www.indiabix.com, they have given answer: If you compile

问题 I have what is hopefully a trivial question that someone can explain to me in simpler terms than what I have already come across. While working through A Tour of C++ (Second Edition) I've been trying a few examples. I'm currently trying to modify a pointer to a string literal in a separate function (I thought it would be easy.....). using namespace std; void test(char *ptr) { ptr = "test"; } int main() { char *p = "abc"; test(p); cout << p << "\n"; return 0; } When using g++ to compile, I get

问题 The following UPDATE fails :- UPDATE table_name SET col_name = varchar WHERE col_name is NULL; The failure message is :- ERROR: column "varchar" does not exist Whereas the undermentioned one succeeds :- UPDATE table_name SET col_name = 889977 WHERE col_name is NULL; I have checked the pg_typeof of the column - col_name is character varying . Kindly help. 回答1: i think you missed quote for string UPDATE table_name SET col_name = 'varchar' WHERE col_name is NULL; 来源： https://stackoverflow.com

问题 I just started learning database a couple of days ago. I'm running into this problem where my value is being recognized as a column, and it's spitting out an error. This is my News table: id | bodyText | url | createdAt | updatedAt ----+----------+-----+-----------+----------- this is the command I ran in psql: INSERT INTO "News" ("bodyText") VALUES ("this is a test"); and this is the error I'm getting: ERROR: column "this is a test" does not exist LINE 1: INSERT INTO "News" ("bodyText")

问题 I just started learning database a couple of days ago. I'm running into this problem where my value is being recognized as a column, and it's spitting out an error. This is my News table: id | bodyText | url | createdAt | updatedAt ----+----------+-----+-----------+----------- this is the command I ran in psql: INSERT INTO "News" ("bodyText") VALUES ("this is a test"); and this is the error I'm getting: ERROR: column "this is a test" does not exist LINE 1: INSERT INTO "News" ("bodyText")

问题 I'm trying to update SQL data but it contains ' so I get errors. The SQL statement looks like this: UPDATE SystemConfiguration SET HeaderScript = '<script> (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],' WHERE ID = 1 I tried to replace the quote with " but I get error. I also tried without quote I get error as well. Any suggestions. 回答1: You need to double the single quotes to escape them: UPDATE

问题 I'm trying to update SQL data but it contains ' so I get errors. The SQL statement looks like this: UPDATE SystemConfiguration SET HeaderScript = '<script> (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],' WHERE ID = 1 I tried to replace the quote with " but I get error. I also tried without quote I get error as well. Any suggestions. 回答1: You need to double the single quotes to escape them: UPDATE

问题 I've been pulling my hair out. I have a very simple postgre database, one specific table has a column named lName (uppercase N). Now I know with postgre I must quote lName since it contains an uppercase N. I am trying to query the database with the following statement: SELECT * FROM employee WHERE "lName" LIKE "Smith" But I am receive this error: Warning: pg_query() [function.pg-query]: Query failed: ERROR: column "Smith" does not exist in ..... What is the issue here? Why is it saying the

问题 I'm coming from SQL Server and I was suprised to see that the following query does not work: DELETE FROM user_job_titles WHERE id IN ( "c836d018-1d12-4507-a268-a4d80d6d3f54", "d0961a90-7d31-4c4c-9c1b-671115e3d833", "62dda420-6e62-4017-b41d-205c0aa82ead" ) where user_job_titles has the following columns: id user_id job_title_id The error is: ERROR: column "c836d018-1d12-4507-a268-a4d80d6d3f54" does not exist LINE 2: "c836d018-1d12-4507-a268-a4d80d6d3f54" I'm using pgAdmin with latest

问题 I created a DOMAIN: CREATE DOMAIN public."POSTAL_CODE" AS character(5) NOT NULL; I tried to set the default value: ALTER DOMAIN public."POSTAL_CODE" SET DEFAULT "00000"; but got the error: ERROR: column "00000" does not exist Then I managed to set the default value using DEFAULT 00000 , but I think it was cast to INTEGER as it shows as 0 instead of 00000 . I tried character(5)[] and {'0','0','0','0','0'} without success as well. How to get a default value as text and not get an error? I used