如何使用为x轴使用多列的ggplot制作条形图？

library(ggplot2)

# 创建一个数据框
data <- data.frame(
  category = c("A", "B", "C", "D"),
  column1 = c(10, 15, 8, 12),
  column2 = c(5, 7, 3, 9),
  column3 = c(2, 4, 6, 8)
)

# 使用ggplot创建条形图
ggplot(data, aes(x = category)) +
  geom_bar(aes(y = column1, fill = "Column 1"), stat = "identity", position = "dodge") +
  geom_bar(aes(y = column2, fill = "Column 2"), stat = "identity", position = "dodge") +
  geom_bar(aes(y = column3, fill = "Column 3"), stat = "identity", position = "dodge") +
  labs(x = "Category", y = "Value") +
  scale_fill_manual(values = c("Column 1" = "red", "Column 2" = "blue", "Column 3" = "green")) +
  theme_minimal()